Related: Expedia has an API... http://developer.ean.com/. Haven't checked it in a while - looks like only hotels are available now (no flights, cars, cruises, etc.)

Of course, not saying that Kayak went through this route - this is just something available to the hoi polloi.

I looked at Expedia for somewherenice.net, and didn't choose them for that reason. Needed to be able to package the whole trip, from airfare to lift tickets, so ended up working with Travelocity.