Meet the KeySweeper: a covert keylogger camouflaged as a USB wall charger that wirelessly sniffs, logs and reports back all keystrokes from any Microsoft Wireless Keyboard in the vicinity. Keystrokes are stored online via a GSM chip. They can also be stored on the device and delivered wirelessly to a secondary KeySweeper within the proper range. The device has the ability to send SMS alerts when certain keystrokes are typed. For instance, a hacker can use this device to get notified when someone is doing online banking on their computer.
If the device is removed from AC power, it appears off but continues to work using an internal battery. Samy Kamkar is behind this cool tool. Since this is an Arduino-based device, you can learn a lot by trying to make your own. You may want to check out Samy Kamkar’s blog to learn more about this project.