Cables, schmables. Why occupy valuable USB slots when you can make iTunes data fly magically over virtual intertubes to and from your home computer? New to the jailbreak world, Wi-Fi Sync introduces over-the-air sync to iPhone devices.
The application works like this: you install a client app on your desktop computer (10.5 and 10.6 Mac only at this time), which you can download for free from the Wi-Fi Sync website. Then, run the $9.99 Wi-Fi Sync application on your iPhone. Your phone will appear in iTunes' sources list as a connected device. You can then sync your device, just as if it were plugged in at a standard USB port.