Alright, I'll add my two cents. Just my own opinions...
First and foremost, don't get so worked up about everyone else's lack of customer service. You can't make the gate agent treat the customers with respect. However, you can compensate for what they lack with some above and beyond service of your own. Once the door closes, it's just the three of us in that airplane tasked with impressing the people we're carrying to their destination. I try to only worry about the things I can control, because there is no point wasting time on things I can't fix.
I honestly believe that the PA is one of our best customer service tools, if used properly. It's not an opportunity for you to practice your comedy act, nor should you make all announcements in a mundane, lack-of-emotion voice. I just talk on the PA like I'm talking to the customer face to face, and I leave out all the techincal jargon. If we're late for bags, I just say, "Ladies and Gentlemen, we're holding for a few minutes waiting for some of your checked bags to make their way over here from the bag room. It shouldn't take too long, and then we'll be able to get underway." A good preflight announcement just tells them the facts. My toes curl when I hear the, "currently in Chicago, the winds are coming from the west and 15 knots, gusting to 25 knots, ten miles of visibility, with some broken clouds at twenty-five hundred feet..." Uh OK, so you can decode a METAR. When do you see any of those things in a Weather Channel forecast? It's a temperature, windy or not, cloudy or sunny. People just want to know if it was a mistake to wear shorts.
I sometimes believe that when it comes to talking to our customers, we feel like we are separated from them. I don't feel that way. Yes, I am taking you where you need to go today, but I'm not better than you. I'm just another human being, and I'm going to talk to you like one. If you need help finding your way, I'll do my best. If you're nervous about flying, I'll try to explain some things to you without scaring you. I sometimes watch pilots in the gate area, and it's like they fear the scrutiny and watchful eyes. They can't make eye contact with their customers. I'm not sure why, but it keeps them from opportunities to interact and make the travel experience more positive for the people we're carrying.
When I'm just sitting around, after accomplishing my preflight/postflight tasks, I'll also do things like help cross seat belts, move the gate-checked bags into the jetway, or help a wheelchair customer off the airplane. Sure, these aren't in my job description, and we can argue all day about the "OJI" angle of it. However, I want to interact with my fellow work groups. When the going gets tough, and "stuff" hit the fan, I'm going to need to rely on them. Do I want them to help out of respect for my epaulets, or respect for me as a person? Do you think they'll work harder one way or the other?
Ed had a great point about flying the airplane smoothly. All that stuff on the ground aside, if you fly your airliner like an F-16, no amount of PAs or bag tossing will make it a better experience for your customers. My toes curl when I fly with one of the "yank and bank" types.
Maybe I'll think of more stuff later. Interesting little tidbit: SWA actually has a lot of information about this type of stuff in the "Pilot Techniques" section of their flight manual. Good things written there!