TweetMyPc takes an interesting idea to the 140 characters by allowing you to send commands that get understood by a program on the remote machine and are acted upon.
There is a long list of commands that can be issues, found at this link, but here is a short summary:
Yuo can even have the PC send results as tweets with the Reply command.
So how does it all work? You install this program and create a new private Twitter account. Make sure this account is quite secure. You then have the private account ready to start watching tweets. The code is freely available to download and start enjoying.