Dutch agency Code d'Azur and KLM have a fun idea. The Must See Map. Instead of asking the twitterverse and Facebook, etc for tips on where to go see and do on your next vacation, you can ask your friends, they'll answer via the same channels, and then KLM will send you a personalized map with your friends' recommendations instead.
Since the personalized map takes three weeks to arrive this does not allow for spontaneity in vacationing. However, there's always this thing called Yelp which is what you're already using anyway.