Bloaty's Pizza Hog: Fansite offering character profiles, quotes, sounds, and pictures. [Flash Reccomended]
Food Courtia: Episode descriptions, pictures, mp3s, news updates regarding the series.
Gir: Adoptions, wallpapers, chip switches, downloads, sounds, coloring pages, a message board, and doodle chat.
GIR's Dog House: Includes episode guide, cast biographies, a small picture gallery, and chip switches.
Gir's Doom Land: Pictures, wallpaper, and music.
I Love This Show: A fansite with an episode guide, cast biographies, pictures, and quizzes.
Implode: Do You Deny It: Fan art and fiction, trivia, scripts, sound clips, quotes, and links.
Invader Cory's Invader Zim Quote thingy: Fansite with various quotes.
Invader Zim: Official Nickelodeon site with character profiles, desktop downloads, sound clips, and pictures. [Requires Flash]
Invader Zim Doom Doom: Character adoptions, pictures, profiles, images, and a humor section.
Invader Zim Ground Zero: Character profiles, episode guide, quotes, equipment, links, quiz, fan fiction, and polls.
Invader Zim Ring: An extensive listing and links to all member sites as well as joining instructions.
Invader Zim Wavs: Sound clips from GIR, Zim and Gaz.
Invader Zim's Secret Lair: Fan fiction, character profiles, games, and pictures.
Lord Krisman's Invader Zim Site: Images of a switch chip collection, fan art, wallpapers, and a message board, and links to episode information.
Melissa Invader Zim Site: Character biographies, an episode guide, and images.
Mission Goo II: Character profiles, place guide, episodes, images, hidden jokes, RPG, Gir shrine, multimedia, chat, polls, and links.
Prepare to be Subjugated: Offers quizzes, downloadable games, a large .wav clip library, fan art, fan fiction, and an expanding collection of screenshots and video.
Strange Nonsense: Images, fan fiction and art.
Temportal of Doom: Polls, quizzes, and a collection of pictures and chipswitches.
The Invasion Is Here: Character profiles, games, video clips, and series information.
The Moose Room: Pictures, episode and character guides, a guestbook, and zim zodes (fan fiction) showtimes.
The Scary Monkey Show Website: Full episode transcripts, hundreds of pictures, and descriptions of every character down to those with mere seconds of screen time.
The Zone: Fansite which offers images, quizzes, and fonts.
ToyKeeper.net Zim Videos: A selection of videos in divx (.avi) format as well as Jhonen fan art and wallpaper.
Your Mom's House: Complete episode list with videos and a comprehensive links list to related 'toon sites.
Zim of Irk: Images, sounds, movies, and personal information.
Zim-ness: Fan site with pictures, sound clips, and backgrounds.