Fairy-Fountain.NET -- Mousey for hosting the site and being a great help with just about everything. I couldn't ask for a better host. She had the subdomain prepared within hours of my application so you can see why I love her, right?!
Calico - The entire concept of an online trading card game!
Games & ScriptsHelpful Hand - MyTCG Script & Hacks
In the Cards - Currency & coupon randomizer as well as several automatic games!
TCG Publicity - Randomizer for non-MyTCG games and randomizer fix for join form
Exposure Forums - Help with coding games.
NeedTakeHave - Doubles Trade-In Mod for MyTCG.
Micki - Show Upcoming Decks Mod for MyTCG.
Steve White's Jigsaw Applet - Java applet for Daimon Kaito's Jigsaw.
Puzzle Maker - Generate word searches.
Absolute Chaos - Card Search MyTCG Mod
Find the Senshi! Idea - Inspired by Rapture
Haru's Cosplay Idea - Inspired by Charm
Image ResourcesGoogle Image Search - 100% serious here. I can't remember most of the sites that hosted the images so I'm just crediting Google. The few that I did remember are the ones that popped up often.
Various Anime Wikis - Pretty much every anime has it's own Wiki page and they're a good source for pictures as long as the images are large enough.
Random Tumblr blogs - Well, Tumblr users take a lot of screencaps...I'd do them myself but finding raw footage takes time.
Zerochan - I usually try to avoid using them but they do have a lot of images. If official anime artwork is low, this site is used as a supplement. However, only images that look like they could be official are used. Pairing decks are an exception - especially for yaoi/yuri pairings.
FanPop - Several users there upload their fanart here, but we pretty much only use fanart for pairing decks.
mangaka-blue - Yes, I use blogs like these for images if I'm too lazy to search for them.
Our Song Screencaps - Nothing is better for an anime TCG than high-quality screencaps!
Eizou Tokuten - Not really an image resource but this is where a large portion of the videos used for openings and endings will come from.
Rubriky @ Sa-yo - Often used for character decks, specifically from VNs turned anime.
Kisuki - Artbook scans for special decks.
Anime Forums Screencap Gallery - Screencaps for character decks.
Yu-Gi-Oh! Nexus - Raw Yu-Gi-Oh! episodes for capping scenes.