From TokyoPop:

After 1000 years of peace, the wolf god Fenris Fenrir has been reborn. She seeks to find the reincarnation of Balder, the most beloved God, as the land of Midgard sinks further into anarchy. They are both key players in the coming of Ragnarok, the time when fate and free-will shall come into conflict as the very nature of the universe is forever redefined.

RilleL:
Based on norse mythology, ragnarök is the term for the end of the world. Christian equivalence would be the last judgement.

The popular Korean MMORPG "Ragnarok Online" was based on this book.

[From Aku-Tenshi]:

In the center on a metropolis city lies a small, shaky-looking house. A normal... Okay... Not so normal high school student, Sakura Tetsu (and his family), who works day and night relentlessly to support his family's living expenses, lives there. All is normal until one day, people from the future, alien pirates from outer space, appear. The underground kingdom claims Tetsu's land. Will he prevail in protecting his own land? Or will he surrender his land into many more invaders to come? Yes... Weirdness and insanity ensues!

Ikewaki Gajirou, nicknamed Gacchan, is the most valorous of the Big 5 in his school. He's a pretty good person. However, he has one flaw that people fear him for...

From Tokyopop:
On a world with no women, the surviving men have reintroduced the female in the form of an android. Called Marionettes, they are built to serve men and are limited in their interactions with humans. That is until a poor boy named Otaru Mamiya encounters a Marionette named Lime. Lime is a Saber model with a special circuit that gives her emotions. When Otaru awakens two more Saber Marionettes, his life as an 'average' man quickly becomes as extraordinary as the lives of his eager, busty new friends.

From Yen Press:

Millennium Academy is a school where elite vampires are trained to maintain balance in a world where humans and vampires, who possess far greater physical strength than their human counterparts, coexist. And commuting to this school is Aldred, the most distinctly un-vampire-like vampire to be found in the entire institution. But when Al encounters Kei, a human transfer student to the school, their destinies become intertwined, and the fate of their world as they know it comes to lie in their hands!

The story revolves around Tsukune Aono, a boy who accidentally gets enrolled in a school inhabited by monsters and demons. He quickly befriends Moka Akashiya, a vampire who soon develops an obsession with his blood, and later meets other girls who soon take a romantic liking to him.

Being a housewife is no picnic, especially if you have to deal with an idiotic hubby, two reckless children, a mother whose hobby is to decapitate moving “things” and those annoying zombies that are always out to have the best bite of you. A hilariously bizarre tale from the king of gag manga: Kenji Hamaoka of Urayasu tekkin kazoku (Super Radical Gag Family) fame.

The story revolves around Wakame High School's extracurricular club, "Sexy Commando Club," which consists of 5-6 male members (one being the high school principal himself), a female manager, and a small mysterious pet (that may be extraterrestrial in origin). The strange and ancient art of Sexy Commando (the roots of which extend back into Japan's Muromachi period) is a martial one; however, instead of focusing on how to defeat an opponent with punches, kicks, or grappling, it focuses on how to distract the opponent. The logic follows that any distracted opponent is unable to fight, and therefore the art of Sexy Commando trumps any other form of martial arts. There are as many techniques as there are ways to distract, though Wakame High School's Sexy Command Club tends to employ the unzipping of the trousers (Elize no Yuutsu).

On the once-peaceful planet of Industria, constant battles have been fought over control of the planet. Astro is a dim witted but kind boy who tirelessly works to feed his "family," a group of orphaned children. One day, after being fired from his most recent job, the prince of Industria, Bulge, appears in front of him. And even more shocking, Prince Bulge looks and sounds exactly like Astro! One thing leads to another, and Astro now has to take Bulge's place as the heir to the throne of Industria! Suddenly, he's faced with the task of bringing peace and harmony back to this war-torn planet!

- Red Hawk NEO

The Mana Tree, the giver of mana and life for the world of Fa'Diel, burned down nine centuries ago. A war erupted between faeries, humans, and others seeking the scarce power of mana that was left. When the war concluded, the drained Mana Tree slept and throughout the many lands of the world mana was stored in ancient artifacts.

Toto, and his pet Rabbi, have set out on an adventure to restore the world, and its mana, to its former self.

The Lands of Fa'Diel are populated with a large number of different creatures, including humans, faeries, demons, the jewel-hearted Jumi race, plant-like Sproutlings and Flowerlings, miner bears called Dudbears, and shadowy beings of the Underworld known as Shadoles. Fa'Diel is also the home of a host of anthropomorphic animals and objects, as well as monsters such as Rabites, Chobin Hoods, and Goblins.

Adaption of the PlayStation game of the same name.

From Tokyopop:

Fifteen years ago, a set of twins--a girl and a boy--was born to the king of Linevan. Shortly after their birth, a prophecy foretold that when the girl turned 16, she would bring about the end of humanity. To avoid this terrible fate, the king ordered the princess disposed of...scrapped!
She miraculously survived and was raised away from the kingdom that would kill her. But now she has turned 15, and the king's guards have caught wind that she's still alive...and they set out to finish the job!

Welcome to the cursed island of Shina Dark. This island is called home by the dark lord Exoda C. Claw AKA Satan. He's as powerful a being as you could ever hope to meet. Feared and hated the world over for the infinite amount of atrocities he's committed. He's.....actually a really nice guy who just wants to chill out around the castle and relax... After a month long nap he awakens to find that the rest of the world has made up another ridiculous rumor and blown it way out of proportion and that has caused his little island to be crowded with a thousand beautiful girls meant to be his mistresses/sacrifices. Worse yet is that since they have set foot on his island they are all believed to be cursed and are now shunned by their homelands. What’s a couch potato Satan to do with 1000 women who wont leave? Who can say?

From Operation Boredom:

During an eclipse, demon Lord Exoda. C. Crown was revived. He is supposed to bring chaos and destruction to the world. The world is panicking, and as a sacrifice to the demon lord, they decide to send 1,000 girls to the demonic island, Shina Dark. However, in Shina Dark, all the legends are lies. Exoda does not sleep with 10 girls a night, and keep the others prisoners. He does not lust for girls, he does not want to cause mass destruction - he simply wants to live in peace. So when 1,000 girls suddenly show up in his island and refuse to leave, what will happen to Exoda, who simply wants to be left alone?

Tenchi Masaki is a shy high school boy, yet honest and hard working. He looks forward to living a basic humble life, taking over his grandfather's shrine. However, nothing is ever as simple as one would want, as Tenchi soon learns. A series of events beginning with the sudden appearance of Ryoko, the space pirate, creates madness in his home. Now he must figure out how to juggle 2 princess's, a space pirate, 2 galaxy police, the worlds most intelligent genius and a Rabbit-turned-Spaceship in his quiet country home.

Heero attempts to live a normal life after the war. But his "peaceful" life is disturbed when someone manages to steal Wing ZERO. He rushes to search for it, and is then faced with an unlikely foe. On all accounts, Ground Zero can be considered a doujinshi due to its lack of consistency and subjected humor. However, it tackles deeply into the characters' morale and philosophies regarding war, peace, and of course, the gundams. Like Battlefield of Pacifists and Blind Target, Ground Zero are *possible* events that take place in between the TV series and the OVA, Endless Waltz.

After meeting the enigmatic woman Hureika in a sideside village during her travels, the beautiful genius sorceress Lina Inverse’s fate takes a dramatic turn. Separated from her partner Gourry, she finds herself swept ashore onto an unfamiliar land. Faced with violent monsters, she is suddenly unable to wield her magic…. But her grand adventures only begin once she is saved by Lyos, a boy who claims himself to be the “Knight of the Aqua Lord”….

Alternate retelling of the Slayers TRY anime.

A re-imagining of Gurren Lagann. In this alternate version of TTGL, Simon lives in Tepelen city and dreams of becoming a Gunmen pilot after having seen the stars through a crack in the sky. One day, he comes across a strange small Gunmen. The hatch opens, and out comes a beautiful girl named Nia.

From Viz: The trouble and fun began when ordinary teenager Tenchi Masaki inadvertently released the legendary demon Ryoko from his grandfather's shrine. Turned out Ryoko was actually a marooned space pirate! Since then, she's become Tenchi's unwanted houseguest, attracting a host of other troublemaking alien women: Ayeka, a haughty alien pricess; Sasami, her mischievous little sister; and Washu, Ryoko's mad-scientist "mother." Add Ryo-oh-Ki, an adorable little carrot-eating spaceship, and you've got one full Shinto shrine!

The planet of Salami is almost identical to planet Earth. Judging from the appearance, there's nothing different from Earth... Except... The sense of beauty is VERY different. Aimi is an orphan living with her step-mother and step-sisters, and she is what we consider as being beautiful, but what THEY consider as ugly. Yet, that doesn't end the story. Just by an accident, Aimi somehow stumbles upon Earth and meets Kyou Naruse, a self-centered person, a full-blown "narcissist. Kyou comes in, smooth and suave like any prince should, to help Aimi off her feet but she calls him "ugly!" Our very own Cinderella Story... or not.

While bicycling to school her first day as a high school student, Renge Ohyama meets a weird girl who on closer inspection appears to be a life-sized doll--not an advanced robotic creation or even a magical doll. Rather, a scary looking middle aged man controls her movements, puppet-like, and speaks for her via ventriloquism. Unfortunately, this perverted-seeming old man and his doll happen to attend her new school. Even worse, is in the same class and sits right behind her. And it seems the doll wants to be friends?!

Eratarou Kamegashira is a normal guy. All he wants is to live his high school years in peace and tranquility, hopefully making a girlfriend or two in the process. However, his brother Maratarou is a gigantic pervert. Due to Maratarou's shenanigans, Eratarou has been having trouble making any girlfriends due to being associated with him. However one day, the beautiful Takahara-san asks if she could visit Eratarou. Will Eratarou be able to keep his cool and win the girl, or will his brother cause things to "heat up"? Find out in the Kamegashira Brothers!