Online travel agency that doesn't suck

Not a single one of the flight-search services has any kind of memory for what you're doing. If you want to poke around, you have to keep re-entering everything; Travelocity will kinda-sorta remember the city you started from, but it will forget you wanted to bring your kids, for instance.

There's no service at all that lets you look for flights from one region to another. What if I'm on the East Coast, don't mind driving a couple of hours, and want to get somewhere in Europe sometime in June? Can't (easily) be done.

What if I want to research a trip, then go back next Tuesday and look some more? It's all been forgotten. The prices I saw last week (or fifteen minutes ago)? Forgotten.

I'm not even talking about anything else, just flights, although a real travel planner online would also be nice.

I can't imagine that wouldn't be a hit. Add forums and maybe some social stuff and bam, you're off to the races.