Revision of DIY Bike Theft Prevention: How to build a bike tracker & theif shocker (might be illegal) from July 16, 2008 - 4:53pm

This shirtless fellow rigged up his own device to track stolen bikes and remotely electrocute the theif.  It involves a cheap disposable phone and a stun gun.  To be able to have your stolen bike report home, you'd need to use a cell phone that can do data... and I'm not sure if any of the Canadian mobile telcos actually have any fair pricing for that.

Oh, and it's probably really illegal to a). rig up your bike to shock people and b). shock people even if they stole your bike.  So you probably shouldn't add the stun gun part.  It's just cool to look at and admire... educational purposes only etc.

See here for the step by step how-to on Instructables.