I recently have rebooted my old manga forums into a One Piece centric forum!
http://opnewworld.proboards.com/
We have several ongoing One Piece RP's. We're currently looking for new members to jump start discussions. We have about seven or so very active members, but we know this isn't enough to keep a forum afloat. We would love to have you by if you love One Piece even half as much as we do.