Whenever I read a recipe online I get this nagging feeling that there should be some widely used open standard for describing recipes that can do all sorts of awesome stuff (like a web crawler such as DuckDuckGo being able to answer "I have a pineapple, cream, and the usual pantry basics, what can I cook?"), but this seems to go directly against the business models of the big recipe sites, so it will not likely see much uptake.