For root users only! If you want to do some of the lower-level stuff with your Android phone, you're going to need ADB, which stands for Android Debug Bridge -- basically a way of connecting your phone to your computer. But what if you don't have your USB cable with you? What if you're phone is right next to your computer, but your nearest USB cable is in your bedroom, and you're too lazy to walk in there and grab it (or your son is asleep right next to it and you don't want to wake him up)?
The solution is ADB Wireless. With this app, if your phone and your computer are on the same network, it's a cinch to use ADB. All you have to do is open a command line on your computer and use "adb connect <IP Address>:5555 and you're connected to your phone via ADB just as if you were using your coveted USB cable.
Of course, you still need ADB on your computer, which usually means having the Android SDK installed. Hit the break for another screen shot, plus download links.