Provide a realtime chat if you can, ie like: https://github.com/isaacsu/twich Give it a timetable so each project has a set time for participants to chat, (the project in question is displayed at the top of a page.) You can also record chats, and offer multiple rooms.

Maybe a Q&A archive for each project, along the lines of http://forum.twich.me/ or http://formspring.me