I read several of the replies (and I'll admit that I didn't read all of them as closely as I probably should have) and here is my response.

Do I get an incentive by not running the APU? The answer is, "Yes." When I am at a hub with cameras pointed at me and/or management walking around - my incentive is not getting that telephone call as to why the APU was running when it wasn't that hot out. Do I get reimbursed for the fuel savings? No.

You talk about people being furloughed, etc. Bear with me for a minute. Did you ever stop to think that whatever mainline you are flying for (i.e. United, USAir, etc) is furloughing their pilots because the budget is stretched thin? By trying to save as much money as I can when I am working, I am indirectly saving jobs. I'm not just talking about pilot jobs - I am talking about the girl in human resources that is married to a pilot, the gate agent that is dating a pilot, etc.

With that being said, I will be the first one to walk outside and ask the ramp crew if they can hook up the ground air. I do this while the APU is RUNNING!. The last thing I want is some elderly passenger who has lost the ability to thermoregulate their body temperature to pass out (yes, I have some medical training). At my company, we are not allowed to leave the aircraft with the APU running. Hooking up the ground air not only helps out my passengers and saves money - it keeps the aircraft somewhat cool for the next crew.

Do what you have to do. With the exception of several stations, I always start the APU prior to arriving at the gate (I don't want someone walking into a running engine). If power and air are hooking up, I shut the APU off. Unless is unbearable in the cabin or if the flight attendants need it for water pressure, I hardly ever start the APU more than 10 minutes prior to departure. Take a look at mainline - they do the same thing. Its well past the time that we should start following the procedures of mainline. This is why we are sometimes looked down upon by mainline pilots - our lack of professionalism.

Just use some common sense. Don't run the APU to try to "prove a point to management." In the end, we all end up paying if we operate in this manner.