Bike locks are all well and good, but if you really want to keep your bike protected, you need to outfit it with a BikeSpike ($150 and up). This small accessory attaches to your bike via a custom water bottle holder, and packs a GPS chipset, cellular antenna, and accelerometer into its small black body. Thanks to all that tech, you can monitor your ride's location using a phone or computer, digitally "lock" your bike and get a push notification if it's moved/tampered with, automatically alert contacts in the event of a collision, and monitor stats like distance, speed, and favorite courses. Just think of it as a combination Find My iPhone/Nike+ for your bike.