How about that gawdawful furry bodywork stuff they used to put on sportbikes in the late 90s? A few months ago I saw a bunch of those cats with furry CBR 929's. It was hideous. I really like those old 929s and wouldn't mind someday buying one used, but those cats couldn't give me their bikes.
Over here in Norway we have something called a Guard System. A GPS tracking device is installed on the bike (secret location decided by you), and Guard Systems traces the stolen car or bike. Your insurance company will pay for the tracing, by aircraft if necessary. As an additinoal bonus you can expect a hefty reduction in your fully comp insurance... Pricey at around $ 1,000.00 + installation, though.
Rig up a conductive section on the seat that is electrically isolated from the rest of the bike. Then hook up a 15,000volt powersupply that completes the circuit when someone sits on the bike and grabs the handlebars.
The only downside here is forgetting to disarm the system before you get on the bike. That's the main reason I've never done it.
Actually , just sending the voltage from the coils would be enough to stop someone. Just some extra wire, and afew switches. but again one will remember to disarm system, after the first time you forget.