The American Association for the Advancement of Science (AAAS) is setting up a new platform for scientific collaboration called Trellis. A key feature is that you can upload papers you want to discuss and anybody in the group can read the paper online: the AAAS takes care of all the copyright issues with the journal publisher. Another feature is that you can control how much noise you get from Trellis. Messages can have up to 2500 characters, but if you have longer text you can create a PDF and upload it like a paper. The same holds for images and videos.
Many AAAS members are teachers: if you do crowd-sourced experiments, you can easily find subjects. The AAAS is also involved in policy making in Washington, in case you need help with that. You can also announce conferences and other scientific events, and use the shared calendar.
Trellis is currently in pilot phase for educators, policy makers, and Section T of AAAS (Information, Computing, and Communication). There are still a few rough edges that are being ironed out. That might be why you have not yet heard of Trellis.
I am setting up a group called Computational Color Science in Section T. However, we are trying out something new. We are making it a completely open group, i.e., anybody with the URL can sign up and participate, without having to be an AAAS member. To join, go to http://www.trelliscience.com/color/. You can invite anybody else you want by giving them the URL and they can sign up.