I love Epicurious for its interactive map of in-season fruits and vegetables and its amazing advanced recipe search. If I want to make something special on the stovetop, that's my first stop. (I'm always careful to check that the recipe is marked "quick and easy", though -- these recipes come from Gourmet, Bon Appetit, etc., so they tend to assume you have time to spend all day in the kitchen.)
Its only failings are that it has very few slow cooker recipes and it can be a little tricky to search for recipes with a specific key ingredient. If I'm planning family meals based on what's on sale at the supermarket this week, I tend to search for "vegetarian slow cooker recipe" + the specific ingredient on Google and rely on the comments/ratings to decide which one I want to make. There are so many fantastic cooking blogs out there with recipes I'd hate to miss, and Google indexes many, if not all, of them.