the alternator isn't really an accesory, but MetroMPG did some testing as to what happens without an alternator belt, you can see those resultss at:
Alternator Belt Remove Test
For racing, you can get electric water pumps, altho they would put more drain on the battery, and if you disconnect your alternator that can creat a problem if you ever want to make a longer trip.
If you want to remove the belt from your A/C I say go for it! I removed the whole A/C unit from my car, and in the 100 degree, 95% humidity we had last week I was sweating a little, but it's good for you.
If you have a large vehicle, I would be hesitent to remove the power steering, because of the high vehicle weight, and absurdly wide tires they often put on those vehicles can make it nearly impossible to steer at low speeds without it, unlike a smaller vehicle like mine, where I can steer at a dead stop with my little finger.
I don't think they amarican car compenies are planing to truely make a hybrid, they are going to make a "mild hybrid" basicly a marking tool to sell more large vehicles that still get poor mileage, basicly make all the things like power steering, and A/C electric, so if you don't use them the vehicle gets slightly better mileage, and then have it turn off when it's sitting at a stop light, overall it will get better EPA numbers, but with how most amaricans drive, it's just a marketing tool.