The iTwinge is a plastic keyboard for iPhone. Not an external thing using the USB port, but a simple overlay for the virtual keyboard.
Obviously, it does not work in horizontal mode. You can buy it from www.itwinge.com.

There’s genius in this one. This small and simple device from thinkgeek.com can easily be hidden anywhere, thanks to the built-in magnet. What does it do ? It beeps. Shortly. Loudly. Randomly.
It’s a bit cruel, but some really deserve it.

If you’ve sensitive data on a CD / DVD and want to make it REALLY unreadable, you need a CD / DVD destroyer:
This USB powered device makes the disc unreadable by scratching its surface. Don’t miss the demo video on usbgeek.com.

We love complex remote control units, but some others don’t. If you share your life with such a person, build your own remote control simplifier using the example below:
This could also avoid you long telephone calls and hours spent tuning everything again…

If you have to work in a place infested with mosquitoes, this could save your day: a USB powered ultrasonic mosquito repeller:
You can buy it from Uxsight.