Hi Dave,
Since drums are my primary instrument and I've been on various drum forums for five years, I'm qualified to give you a couple of recomendations. (Even if I'm not qualified, nobody else has come forward.)
So...
The drum forum which is most like TB is probably DFO.
[DFO] Drum Forum - Vintage and Modern Drumming Community
DFO is is a large and busy forum like TB and you'll likely be welcomed there. I don't recall specific threads about working with other musicians, but I'd think that one would be welcome.
DrumChat is a forum that I haven't been on too long, but it too has a decent following and is a fairly friendly forum.
DrumChat.com - Drummer Forum / DRUM FORUM for Drums - Powered by vBulletin
My personal favorite is Drum-World.com.
Drum-World.com - Let's talk drums!
It's a smaller forum, but is particularly friendly. New members are welcome and discussion can get as deep as you want it to. Full disclosure makes me mention that I am a moderator there.