Bike turntable / dolly recommendations

[fazersharp]

I use one of these
  http://www.matturntable.com/online_shop.html
  I've had it for years, they last forever, they're a bit pricier now than when I bought mine though.

I made one of those a few years ago cause I didn't want to pay the price. It was two sheets of 3mm plastic with a flat flange head machine screw bolt in the middle I found I needed to glue a cheap rubber car mat on the top disk because the stand would slip when I twisted the bike around. To reduce friction between the two discs I used some grease. It worked ok.
If you can set it into the floor you could make something better with plywood and ball baring wheels. I say set it in the floor as it would be quite thick.