I've been posting on Something Awful's forums for a few year nows but usually just in the video game section. Recently took a look at the "traditional games" sub-forum and it's got some awesome play-by-post rpgs going in it. :) Take a look through:
Traditional Games
It looks like they take forever to get finished, but there's some real gems in there and it's fun to sorta "sit-in" on another groups game. Some of the GM's go all out with the visual aids.