I've been yelping quite a bit lately. I get to opine about the places I go and give them ratings and talk smack about them if I feel like it, which is actually turning out to be a great writing exercise if I have other work to do that I can't quite get jump-started.
The site is really helpful if you want to check out public opinion on anything from restaurants and bars to dry cleaners and beauty salons. We used it a lot on our last trip to New York, to confirm or deny locations and to get a general vibe for what people thought about restaurants, specifically. It's good if you're traveling somewhere new. I know I'll use it like crazy for Chicago places.
Go ahead - yelp yourself. It's liberating.