I've been playing on PlayWSOB.com which I found through this forum. It's been a good experience so far. I've won some freeroll tourneys and play small stakes cash games and matches there. I also play on grid gammon but you'll need an invite to register.
I believe Gammon Empire and Play65 are run by the same people. The biggest difference that I've seen between the two is that one's called Play65 and the other one's called Gammon Empire.
Don't know about PlayWSOB, but I think if you sign up at TrueMoneyGames with rakeback you get rb for your backgammon too. They're on the same network so same player pool.
So, do they have the freerolls from WSOB if I go through TrueMoneyGames?
If I win money in a freeroll on WSOB can it be used to play on the TrueMoneyGames network? I'm guessing the answer to both questions is no.