I run several Pbp's (one on here). The gap between posting and rolling, it's really not that bad. You just have to trust your players to know what to roll, or get used to the slow pace of the game.
I would be pretty interested in a trading/ small ship sort of game... that or a mercenary commander type of game, where we build, run and command a mercenary unit...
I'm pretty easy though. But as I say, I cant do IM games, just PBP...