The Grey Archive, located (as of January 2006) at www.greyarchive.org, is a website dedicated to various science fiction\fantasy erotica (although erotica may be too charitable of a description).
The archive includes such categories as fantasy, science fiction, superhero, anime and manga and video games. Each one of these has several dozen to a hundred stories. I personally haven't taken the time to read most of these stories, but there seems to be a lack of literary effort common to online erotica\pr0n. However, the fact is that the entire idea of reading descriptions of having comic book and video game characters having sex is so ridiculous in the first place, that no literary effort is expected. Just enjoy the goofiness. Also, if you are one of the many netizens that still have the common decency to be affronted by the idea of online pr0n, you can happily read these stories, since they are so goofy and so badly written that they barely count as pornography.
The site is quite technically well done, being well laid out and having no banners, pop-ups or java fuckers. If you have ever wondered what exactly would have happened if the Final Fantasy games had solved the question of whether Moogles are anatomically correct, this is the place to go. If you are over 18 that is!