A good friend of mine brought Ohm Studio to my attention a few weeks ago, and it looks really cool.  Currently in beta:

Ohm Studio is the first real-time collaborative digital audio workstation. Start a project, invite musicians and make music together. It’s as simple as that.
Download the application and join a worldwide online cohmunity of musicians and producers.

Ohm Studio includes a ton of their own plugins what work in everyone’s project. If you want to use your own 3rd-party plugins you can do that as well with a track freeze option. The DAW is still in beta and definitely geared towards electronic musicians but I think with the inclusion of some more wave editing options and other tweaks Ohm Studio could be a realistic option.