Beatrush's Collection of Cels

Anime Cel Incognito - The most comprehensive Slayer Cel collection out there.
Berserk Hunter - A terrific collection of Hunter X Hunter cels.
Cel Addicts - Fellow El-Hazard & Burn Up W collector but also collects a wide variety of other series.
Celluloid Cel-Out - Look at his stuff and feel jealous it's not in your collection.
Jaug's Cel Jungle - A "unique" collection of cels.
Lone Turtle's Cel Gallery - Fellow Black Lagoon collector but also collects a wide variety of other series including a great Mezzo Forte collection.
Mokman's Macross & Robotech Cels - An amazing collection of Macross Cels.
Nene's Gallery - A great collection of cels from BGC and various other animes.
Ronin's Cel Gallery - Fellow Shayla Collector but also has a lot of other great cels.
Sylia's Fighting Angels - Lots of BGC and Street Fighter Goodness.
The Wandering Student - A great collection of Golden Boy cels.