Sentiment: Strong Sell
I agree about LNKD and GRPN they both stink, just awful ideas, not sure about ZNGA and Z but YELP and FB will prevail.
LNKD is most likely to survive. The only one that has VALUE. & Prospered from a sensible underwriting.
How you can say that? I am sure you work for hedge fund, who owns YELP or FB. FB is waste of time, and so is YELP. Their practices are under scanner.