Open Platforms (Internet companies offering Open API not only for a single product, but also cross-product APIs)
Group Buying
Online Games (game center)
Microblogging
IM (instant messaging)
BBS (online forum)
Q&A (or Social Q&A like Quora)
e-Commerce (does not include group buying sites)
Video (sites with video uploading
Music
SNS
Blog
LBS
Light Blog
Consumer Review
Wiki
Business Social Network
