This might have little to do with social media per se, but one of the tools I use a lot for collaboration, both in my education and for work, is Dropbox, a handy little service that 1) syncs your files across all your devices 2) makes it easy to share stuff with the people you need to share with and 3) keeps a backup copy of your stuff on the web.
You get 2 GB of space free and a little more if you invite people over (and of course a lot more if you pay for it).
The reason I'm bringing this up now is that I just found out that if you have a university email address, they'll double the space you get for referrals from 250 MB to 500 MB a pop if you register yours (and they do it retroactively). I tried it out and it works for kth.se addresses. So if you're already using Dropbox, head over to www.dropbox.com/edu and double up!
If not, I recommend to give it a try. And I wouldn't mind if you used my referral code to register. ;)