I've been thinking about a way of increasing bike security when needing to lock a bike up at a store, restaurant, restroom, and so on:

Webcams can today be bought with an integral WiFi "transmitter". What if one of these cameras were to be mounted on the bike somewhere, and configured to send the live video feed via WiFi to an iPod Touch, iPhone, Android phone, or other such device? The rider could keep glancing at the video feed to see if anyone is messing with her bike.

Where should the camera be mounted? On the handlebars looking back at the face of a potential rider? On the rear (or front) rack positioned to have most of the bike in the camera image? Under the saddle looking down (the bike I'd use this can only be locked up near the bottom bracket)? Attached to the U-lock so it can be easily stowed in bag when not in use, and have the image get jostled if the lock is being messed with? On the front fork as if it's a speed sensor, and looking back up at a possible rider?