A cookie cooling rack!
After some late-night cookie baking, you might plop your sweet chocolatey cookies down on an elevated wire grid, like the ones in the photos below, to cool them down enough to spare the roof of your mouth from third degree burns. It works because you get cool air moving all around.
You can use the same cooling rack to keep your home theater components cool, too. Just place a small cooling rack under each box or console on the shelf. They can be had for just a few bucks a piece, and come in so many sizes that you're sure to find one that fits your shelf and can hide under your components to maintain a clean look.
Cookie cooling racks also work great for those nights you want to watch a movie on your laptop in bed. Putting your laptop right on the covers is a sure way to get it to overheat, but placing a cooling rack underneath can help keep air circulating and keep your machine at a good temp.