Yelp
Read what "real people" are saying about restaurants, hotels, nightclubs, etc. in New York, Seattle, Phoenix and 21 other cities, or submit written reviews of your own. The site combines strong local search tools (such as Google Maps) with a social networking approach — already the site is teeming with "Yelpers" eager to share — and so the more user-generated content it compiles, the more useful it will be for anybody who's looking for a good time in one of these towns.