If you're looking for a place to build your own social network, Ning probbaly comes to mind first. But the fastest growing DIY social network platform out there may be GROU.PS.
GROU.PS, a do-it-yourself social network focused on moderated online collaboration has steadily gained an impressive amount of users and added compelling features to its application. The social network platform has just hit 2 million users, adding another million members in just 6 months.
TechCrunch also points out the variety of Collaboration tools GROU.PS provides for its users. The company has raised $2 million now in startup funding. It will be interesting to see how quickly it gains brand recognition.