Yeah the only innovative ones are Soundcloud and Gidsy. Then there is www.workhub.com, they are awesome and awesome founder, but they are still in beta. Researc

Yeah the only innovative ones are Soundcloud and Gidsy. Then there is www.workhub.com, they are awesome and awesome founder, but they are still in beta. ResearchGate is also big, but they are more a data startup. Wooga and Hitfox are the other two big ones, but they are game development companies, not a "real" startup.