I concur with the 'hogging the overhead bins' complaint. I just got back from a business trip that had me on a few internal US Air flights across the country, and apart from the last flight (which was a half full 767) the luggage bins were completely full on every one. It annoys me both that airlines charge such exorbitant fees for checking A bag, and also that people still pack the same amount of crap and take it as carry on to avoid those fees.
One of my flights was on an Embraer, so not a huge plane. The seats were 2+2 and there was pretty much one overhead bin for each 6 seats. I found my seat, opened the bin to put my laptop bag in (I had checked my other bag) and found that it was completely full, with 2 suitcases and 2 very large 'handbags' belonging to the ditsy two females sat behind me. I swore under my breath, but just loud enough so that they could hear me....they just giggled. I had to squeeze myself into the seat with my bag under the one infront of me, which was most uncomfortable for a 4 hour flight.
Countless other internal flights I've taken we've had to queue on the jetway to have our bags tagged and thrown in the hold because there isn't a single spare inch of overhead bin space left. On medium to full flights, I'm sure the fact that people try their hardest to not check bags must add 5-10 minutes onto the boarding process.
Another gripe is how selfish some people are in general. Coming back to Philly the other night I had a connection in Charlotte to make. We left Kansas City 45 mins late, so by the time we actually pulled into the gate at CLT I had 5 mins to the scheduled departure time of my next flight. The cabin crew knew some people had connections to make, so made an announcement that would all passengers NOT making connections please remain in their seats until those who WERE making connections had exited the plane. I was half way back in the plane, and as soon as the seat belt sign went off EVERYBODY infront of me, with the exception of 3 or 4 people, stood up to get off. I looked back, and there were only a couple of people who had remained seated. Just rude!
My next complaint is a new one and I'm gonna start a new thread!