websites/software meant for online collab

I'm about to work on a musical project of sorts with an old friend and amazing musician who I met in college. He's in another state which makes it a little hard. I'm fairly technical, so the last time we attempted to do this, I used a remote desktop product to go into his computer to help him set things up. He's got pro tools with an mbox type of setup, I'm more of an ableton guy myself. Also he's on a mac, I'm on a pc. Anyway, I was wondering if you guys have had any success with any websites/products that allow for online collab. We're probably going to use Dropbox to swap audio and midi data, but I'm always looking for ways to make these things simpler. Anyway I just found out about http://www.ohmstudio.com/ which looks like it's basically the same concept as google docs, except with a DAW rather than an office suite. It's in closed beta right now, I requested a login but who knows...

So whats the scoop guys, Drop box + audio files? or is there a better way? And is there any way to do a real-time online jam that is easy to set up? Couldn't get Ninjam to work for me...