Visually that kind of interface is very appealing, but fares may be misleading... once you start the booking process, you will end up with completely different numbers. Typically, a featured "as low as $" air fare is a red eye, 8 hour connection time etc. I was going to output specials myself too, but then commented them out - as they hardly ever apply.

That being said, Kayak does have a great UI, and their iOS apps are eye candy.