Very interesting thread for a very popular upgrade. I might revise my own install with a few of these ideas....
I pulled our old CRT boat-anchor out of the front cabinet a few years ago and replaced it with a 22" combo LCD/DVD player mounted to a 3/4" sheet of painted MDF. I REALLY wanted a bigger screen, but the two cabinets on the sides swing up and are frequently used. So I had to go narrower, which meant about 5" open space visible under the TV into the bottom of the old cabinet. That proved a blessing in disquise, as I was then able to stuff my older, unused receiver behind the TV to power a surround sound system. Later, I was even able to stuff the big system sub-woofer box behind the TV by setting it on top of the receiver with a couple of 1"x1" feet between the two.
Its surprising how little "unused" space is left-over from the factory design these days. Or actually, since 1997 in my case. Every nook and cranny has something.