Simmer (formerly Foodie) - Yelp, but for every dish on the menu
Facebook Local - Discover places to go and events happening near you
Spoon University - Food network for next generation.
Foodie Advice - Get suggestions on what to eat during your travels
NYT Cooking - iPhone app with 17,000 free recipes from The New York Times
Foursquare - Foursquare is all about helping you find new ways to explore your city.