The best way to prevent bicycle theft, is the "better lock"/"better bicycle" approach. No bike lock is invincible, so put your bike next to a better bike with an inferior lock (dings in the paint helps with being a less better bike btw, bike thieves are usually idiots). This is the same idea as how to outrun a bear -- just be faster than the guy next to you.
To that end, Hoofnagle (link via Schneier, god of security) has listed various measures one can take to make identity theft harder: EPIC West: Electronic Privacy Information Center West Coast Office: Hoofnagle's Consumer Privacy Top 10.
Implement these and the thieves will take your neighbors identity instead. This would be wonderful if your neighbor was, say, a US senator. (Note to Senators: Schneier says we need to make identity theft very expensive for banks -- then it will end. I believe that too.)
I'm impressed with the list. Most of them were new to me, and most are easy to apply. Recommended!