Check out this fun robot which was made by Ken Lim, it is designed to monitor your Twitter feed and then react to it, the Guardian Robot.
The Guardian Robot is designed to encourage you to interact with posts it find on Twitter, and it monitors Twitter for happy or sad updated from your friends.
The Guardian Robot can even send a Retweet on your behalf from its own Twitter address @guardianrobot.
It was made using two servos, two microswitches, and a few other parts and it cost Ken around $70 to make, check out the video of it in action below.