The handy things thread!

Decided to start a thread where people can share the handy hacking things
they find on the interwebs!

This is a pretty neat (and cheap) breakout board for the mbed, taking
ethernet and USB out to handy connectors, and adding a microsd socket
http://www.coolcomponents.co.uk/catalog/product_info.php?cPath=23_29_41&products_id=608