CookingByNumbers.com is an ingenious little UK-based site that will put the contents of your refrigerator and pantry into a formula and spit out recipes so you can cook with what you already have. Brilliant!
Tom Tuke-Hastings, the site's creator (and author of The Art of the Vodka Jelly) says "Don't bother going shopping, let's cook with what you have." Amen. This is a great resource for New Yorkers who don't have the energy to shop, but who are committed to cooking in more often.
The only drawback is the list of ingredients is fairly limited (and English... Digestive Biscuit or Tinned Tuna anyone?), so you have to use your imagination a bit. Also, don't expect Epicurious-grade recipes, the site's database is a bit more home-grown.