Great posts in this thread! Just stumbled across it and figured I'd post my own project also. Although its similar to the other designs here (basically the 3 cube box setup), I did a few design details that may interest others.
#1: I used some thin strips of wood on left and right sides to simulate a "faux panel" type construction so as to give the finished product a more "professionally built" look to it.
#2: I added 2 lengths of PVC pipe to connect the left and right sides so as to create seperated conduits for signal and power cables going from Tivo/DVD to the receiver.
#3: I built the doors by routing out some wood strips and using bathroom caulk to secure pieces of glass into the doors. The glass was really cheap (like $8 a piece), custom cut.
Also of note ... I didn't do any fancy "biscuit" stuff or dowels or anything ... I just used 90 degree metal brackets and straight screws and basically all of the strength of the unit is created by the backboard being nailed to the vertical supports. Also note, I used Home Depot "Behr" paint and I highly recommend AGAINST this product because it produces a very soft/markable finish, even after 6 weeks of cure time.
I'm gonna build out the rest of the "entertainment center" when I get some time (see inset picture on 1 of these posts ... guess I gotta post 3 times to get 3 pictures up ...)