Scosche flipSYNC USB 2.0 to Micro-B/Mini-B USB Keychain Cable - Charge & Sync MP3, Cell Phone… for $6.99 + free shipping
This is a really cool thing to have on your keychain. It's about the size of a key fob, but hidden inside are connectors that you can use for your smartphone or GPS. One side is USB 2.0 to plug into a computer. The other side gives you a choice of USB Micro or USB Mini, for your smartphone or other device. Great for data tethering!