Not sure if this should go here in the social science department or somewhere else but recently found this over one of the ones mentioned about a little while back in one of the shows. Guessing if other people find other play-by-post sites, this would be a good collection spot for them looking to try it out.
The one I'm in now is working with the Invisible Castle for rolling dice/stats.
http://invisiblecastle.com/
Somehow spotted this a little while back but then lost it in the forest of stuff at YSDC.
Play-by-post@YSDC
http://www.callofcthulhu.org.uk/
play-by-post sites
"That's funny, usually the blood gets off on the second floor." -Mr. Burns in The Shinning episode (Treehouse of horror V)
http://rpol.net is a good one and has been around for a while.
http://www.rpggeek.com has forums dedicated to PbP.
http://www.rpggeek.com has forums dedicated to PbP.