Reading digg, stumbled upon set of Tricks to Keep Your House Cool this Summer. Immediately remembered a non-trivial observation I made in my old house: amount of heat produced by a stock ceiling fan, or a few desk fans, can easily overcome the subjective drop in temperature caused by increased air circulation (the temperature rise was actually measured, it is not a guess).
This is not necessarily always the case - the smaller the room, the more pronounced is the effect. Or, should I say, the easier it is to measure it...
Original observation is a part of the DZ article called Hot Summer of 2003.
Another argument worth repeating - any heat producing device in your house (fans included) makes your A/C work harder, so not only you're not improving situation, you're making it worse.
A tangent - yes, you can vent the heat generated by your equipment outside, but that opens another can of worms - negative pressure... But that's a different story for a different time.