Get a little computer fan or two. If there is room inside your amplifier you could mount them in there, but I wouldnt reccomend doing that unless you know what youre doing. Just mount them outside of the amp, facing it of course..
Only works if you have A/C //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif Not all of us do...
The CPU fans are a good way to do it. Run a Bosch-type relay from the remote wire, so you can switch them automatically with the head unit. The12volt.com has a good tutorial on how to wire them...