IronJungle built this Twitter robot hand and wrote a detailed explanation describing the build.
Control a Robot Hand by sending a tweet to @OurCatDoor. The Robot Hand understand the following commands. If your tweet includes one these commands in the text, the “Hand of PI” obeys your command. Valid commands are (lowercase):
one (holds up one finger)
peace (shows the two finger peace sign)
three (three fingers up)
hookem (if you are a Texas Longhorn fan this one makes sense)
fist (the Hand of PI gets ready to fight)
open (ready for a ‘high five’)
finger (well… this will be the most tweeted command)
Via Hacked Gadgets.
Check out the video after the break.