Amplifier Cooling Suggestions?

My integrated amp sits on the middle shelf of my rack. It has reasonable clearance and gets adequate air flow. I'm not concerned about the amp overheating at my typical listening volumes. That being said, cool is always better. Do any of you guys supplement your amps' factory cooling solutions with additional cooling? If so, what? If I used supplemental cooling it would have to be quiet, non-invasive (no case modifications) and cheap. I was thinking about getting some high quality computer fans and velcro-ing them to the slots above the fins to draw more air out of the case (aesthetics be damned), but they use molex power connectors and I'm not sure it would be all that effective anyway. What do you guys think?