DAE Built In
A few of the major music sequencing applications that are out there have ways to collaborate online built into them
Reaper Realtime Music Collaboration (Ninjam)
Ninjam is a live realtime(almost) music collaboration tool built into the increasingly popular Cockos Reaper audio sequencer. you can also run Ninjam as a standalone application. The idea is you connect to a Ninjam server (you can setup your own Ninjam server from your home machine if you like) and browse live jams happening live on the server. if you like the sound of one you can join in. You can then send a live audio stream from your own machine to the server and play along with the jam. Because there is an audio latency caused by attempting to jam live over the internet Ninjam delays the received audio until it can be synchronised with all the participants. If your interested to know more chek it out Here
Steinberg VST Connect SE Performer
Steinberg Products (Cubase and Nuendo) have had a means of Online Collaboration built into them in various shapes and forms in the past. This latest solution comes as a built in plug in with the addition of a stand alone application so that users with Steinberg products can collaborate with users who do not run Cubase or Nuendo. The idea being that the user running a Steinberg sequencer is in a producer / engineer mode and the remote user is the player / performer. The remote user will be able to hear the audio coming from the engineer end and will play along, which will be recorded into the Steinerg sequencer. it includes talk back feed and webcam so should make for a good live collaboration. Find out more here
Pro Tools / Gobbler
Pro Tools (as of version 10) have teamed up with Gobbler who we have talked about in the file sharing section of the site. This will allow you to seamlessly back up your pro tools audio to the gobbler servers from within sessions. And of course this will also allow you to share projects with other users if you wish to collaborate.