BikeSpike is constructed of most of the same sensors as a smartphone, including a cellular connection, an accelerometer, and a GPS chip. It's a little box you clip onto the frame of your bike (cleverly, you can also get a water bottle holder that disguises the box, stopping clever thieves from just ripping the box off). You pay a monthly fee--either $7 or $13 per month, though if you fund the project on Kickstarter, you'll get a discounted fee for life--and the BikeSpike will keep you up to date on the whereabouts of your bike. You can "lock" it, which just means you get an instant notification if the bike is moved from its parking spot. Handy!