For me, one would think some of the small third world airports, but in terms of passenger terminal, it is Ellington Field when CO express flew from IAH to EDF. Little shack with the counter, TSA screening and waiting area all in what seemed like a little trailer. That was a nice way to rack up some extra miles though! Although a 15 minute flight accross the city did seem quite silly. Too bad I hever got bumped...wondered what kind of compesation they would offer for such a problem...