Now from you twitter account your could send various commands as twits on to your system which it would recognize the command and act upon. There are two application that i am sharing below.
1. TweetMyPC : Using with a user can then initiate the shutdown, restart of logoff the system by updating the status at Twitter. TweetMyPC is freeware, Windows only and requires .NET 3.5 or higher on your system. TweetMyPC checks for status updates every minute and runs most of the time in the Windows system tray.
2. TweetMyMac : This more for Mac users, using this tiny application you can remote control your macbook. Infact this has more additional command options, some interesting ones are listed below.
a. iSight - Snaps an image from your Mac's iSight camera. Your Mac will then reply with the picture posted on TwitPic.
b. open [App] / quit [App] - Opens/Quits the application. You do not need to specify the apps path, but you must enter it's full name, eg "open Address Book".
c. screensaver - The screensaver will be activated on your Mac.
All the above with other basic commands like shutdown, restart, sleep, etc..
You could download the TweetMyMac application from