I think, without a doubt, the one I visit most often is Budget Bytes. It's written by a woman named Beth, who's obsessed with food and math. Each recipe comes with approximate costs for the whole recipe and per serving. She even figures in the cost of salt and pepper!
Most of her recipes are pretty easy to make, she gives lots of ideas about stretching supplies, and she's thoughtful about different food preferences (meat recipes, as well as vegetarian, and vegan).
How about y'all? Which blogs do you check when you're looking for a recipe or food idea? What are some of your favorite recipes on those blogs?