I strongly believe that doing efficient input/output is a crucial task for a computer.
Here is just a subset of devices I worked with over time. You’ll see the collection growing.
The photos have notes on Flickr.
An (unfortunately) somewhat broken Matias halfkeyboard
A Wii Nunchuk
With just a some small additional electronics they all can be interfaced to an iPhone / iPod touch via Bluetooth.
To be continued.