Kayak

What makes us different is that we’re specialized. Our tools are made to deeply understand things like airfares and hotel stays. And like a travel site we have flights and hotels. But we’re very different from most travel sites because we don't actually sell plane tickets, hotel rooms, or anything else.
KAYAK lets you compare options, and when you find something that fits your budget and tastes, you book it where you want: at the airline site, from the hotel, or from a travel agent.