I second the live chat. Be it voice, text, video, whatever. With separate 'channels' for particular discussions. This could work out much better than the PM system.

I use video chat (skype mainly) to demonstrate concepts and show things. Video chat would be nice, but I understand that not everybody is legal. Tinychat seems pretty good to go, if you don't want to broadcast your face you don't have to, you can just chat in the text box.

Major agreement with Rusty - chat. Faster communication means a chance of less overall clutter in the forums and better post quality. Also, less thread repeats.