Google Reader Pedal: hacking a USB keyboard

Matt Richardson says:

First of all, thank you for writing Made by Hand.  It was such a great read,
and it got me so psyched up to start making stuff… anything I could
think of!  It also got me motivated to put together a few video
tutorials, but my most recent one makes me the most proud.  It's a
"Google Reader Pedal," which I made for a friend that wanted an easier
way to scroll through her unread items on Google Reader.