I've never had my bike stolen (knock on wood), so I'm posing this question out of curiosity.
If your bike was stolen and then you either see someone else riding it or spot it locked against a pole or bike rack, what would you do?
1. Make sure you have a record of the serial number (receipt / police report).
2. Follow to parking spot.
3. Check serial number while locked up.
4 (or 2), call police for assistance.
5. Don't commit assault http://www.chicagotribune.com/news/local/breaking/ct-5-charged-with...
6. If you see it for sale online, arrange for police assistance nearby when you go to view it.