I have an open type rack. So I just put a pedestal stand (garage sale $5.00) and adjusted the hight and angle so that it blows air away from the AVR and amp. Works like a charm, in fact, after the first use, I was pleasantly surprised when the two were actually cool to touch.
The only downside is the noise. Not a problem when listening to active passages, but I can definitely hear it during very quiet passages.