I decided to take some temp readings since no one had posted any. This are from my VSX-32 after watching Iron Man 2 at -0 volume setting. The room is approx. 12x12 and the receiver is in open air. I took readings at a few different points.
transformer - 112.5
Heat syncs - 103-104 measured at different spots of the heat sync
Ambient temperature was approximately 76 in the room, but did start at 74. So the receiver combined with a 50" plasma, laptop, and other components raised the temperature approx 2 degrees, but this IS a small room that is a floor above the HVAC thermostat and is not central to the HVAC system. I received similar readings after my 5-6 hour Halo: Reach streak. I believe these numbers to be conservative considering, the receiver was only warm to the touch, and that my laptop (on my lap) has reached temps of 120+