Yeah, I'm in the process of designing an AV console for my future dedicated media room.
Nothing I've seen prebuilt has done it for me as far as style (I'm looking for modern, but not the Miami Vice look that seems to be available).
So I've been using Google Sketchup to make a model that I'll have a carpenter make for me. I'll buy some pre-made parts, like a TV mount, but everything else will be custom.
I'm thinking of using layers of baltic birch plywood for the material. Sounds odd, I know, but there's some pretty bitchin' stuff you can do with plywood if you treat it right.