ITA is awesome, but their value isn't their interface so much as they supply the fare/availability data to practically everyone (Kayak, Orbitz, fly.com, and us, through via Orbitz).
I've got a very different travel idea, and would love to be able to try it out, and send everyone to Orbitz to book it if they end up finding what they want on my site.
But without the data it is very hard to experiment in making a better travel site.
For bootstrapping a travel search product, you're best to get busy building crawlers to scrape airline websites directly.