This is a good topic - no one wants their bike stolen.
Recently a friend bought himself a new bike. Just by looking at it you could tell it was expensive - not a good thing. We decided to make the bike as visually as unappealing as possible.
1.Sanded off the bright flashy paint - slapped on flat black.
2.Took a Dremel tool to the various components and got rid of the silly logos - in this case SRAM in big white attention grabbing letters.
3.Removed the various stickers from the rims, and painted the rims flat black.

With any type of luck rust will start forming and bleeding all over the frame within a year of two, a good thing.
This bike will pretty much disappear in a sea of bikes that no one is interested in, it barely needs a lock.

My bike is pretty much in that state: flat black, no logos on anything and plenty of rust. Last summer on a 3 month tour of Italy, I never worried about anyone stealing my bike, it's practically invisible. All I carried was a small u-lock (also flat black), and only bothered to lock my bike in big cities, otherwise I never bothered to use the lock - no one wanted anything to do with my ugly bike.