Norwegian Airlines. Check out why: http://www.enjoythemilk.com/2007/06/banned-norwegian-airlines.html
I asked a similar ? last year...http://forums.digitalpoint.com/showthread.php?t=144617 We use Continental for the most part b/c they offer good direct flights from Houston to Hartford (CT). Austin sucks b/c 95% of the connecting flights go through DFW...which is why we'll drive 3 hours to HOU for a direct flight. We used Frontier one time to our trip to CO, very impressed with them. They are a regional airline out of Denver...great planes, service, etc.