It's... Gravitation
Contains character profiles, manga summaries and translations, anime information, soundtrack information, image gallery, doujinshi, and a listing of various other merchandise.

Wild Radiance
Story summary, author information, synopsis and screencaps from each television episode, and links to other related websites.

Smashing Blue
Character descriptions, screencaps from the episodes, and information on where to get the manga, OAVs, and TV series.

Sleepless Beauty -- A Gravitation Site
Character biographies, seiyuu profiles, and mailing list.

Sleepless Beauty
Contains episode transcripts, fan fiction, character guide, and lyrics for the series.

Seven Days: Gravitation
Fan sub reviews, analysis and trouble shooting, CD information, and links.

In the Moonlight
Fan works, downloads, manga translations, pictures, profiles, and links.

Gravitation
Screenshots sorted by episode.

Gravilicious
Clique for fans of the series, with rules, code, member list, and how to join.

Inryoku: A Gravitation RPG
Inryoku is a LiveJournal-based RPG. Its intention is to dwell deep into the lives of your favourite characters, offering you a poignant glimpse into their minds and their hearts.

Gurabiteshiyon.net
A collection of fanfiction catering to multiple tastes and pairings. Read the work of others, or upload your own.

Dare to Dream
Story introduction, characters, episode summaries, essays, manga information and scans, buying information, kumagoro tribute, OVA information, multimedia downloads, images, fan works, and links.

Best of Friends: A Gravi Site
A site dedicated to the anime Gravitation mostly Ryuichi and Kumagoro. Lots of screencaps, character profiles, yaoi fanfics or maybe non-yaoi fanfics (Submit yours!).

Gravitation Anime
Gravitation fanart, animated gifs, manga pictures, episode lists, video clips, and realplayer files.