Foodpairing is a beautiful web app for exploring new flavours and food substitutions. Say you have fresh salmon on hand or some extra sharp cheddar. Use the Foodpairing explorer tree to find ingredients to combine it with, and then even more flavour combinations.
Like Visual Thesaurus, but for food and drinks, Foodpairing is designed to inspire you in the kitchen. You can search for your main ingredient and filter by category and subcategory, or start your dish or drink by choosing the main ingredient from the Foodpairing tree. Then select a complementary ingredient from one of the branches. Foodpairing matches ingredients by major flavour components (see the science behind it here).
The site also features some recipes, like "Broth of sweet onion, onion confit and cream cheese" and "Barfood: Grey Goose l'Orange — ginger — truffel" (the site is sponsored by major food and drink brands). It's less of a recipe site, however, than a flavour mixing board.
Though targeted towards professional chefs and mixologists, if you're a food enthusiast or just tired of the same old food combos, Foodpairing can be great fun. The free account gives you access to about 100 Foodpairing trees; a paid account ($US15/month or $US129/year) is required for the complete database. (If you're interested in flavour combinations, by the way, The Flavor Bible by Karen Page and Andrew Dornenburg, is a great resource on the topic in dead tree format.)