Nothing terribly bad. Way back... had a several-hour long ground delay on an Allegheny flight, stuck in a 727 staring out at the tarmac at EWR.

Had a nine hour flight delay at STL, which was almost terminal boredom.

And missed a connection once at DCA since the little shuttle bus running between the two US Air concourses was down due to "maintenance reasons" (turned out the problem was "driver was on his lunch break") and had to leave the secure area to get to the other concourse, missing my connection since the lines were Disneyland long.

A WN flight from PHX to ONT that involved three equipment changes. I could have driven to ONT in half the time.

And while it's more of an airline problem than an airport one, one of the best was IAD, where United Express VDBed me off of a flight because it had "too much luggage", but never entered it in the system, and then they had trouble rebooking me since "You already flew to MHT. You *can't* be here!" That ended up being about 8 hours hanging around IAD arguing with the customer service people.