TweetMyPC is an open-source application developed by Shoban Kumar, a Client Application Development MVP from Kerela, India, which allows you to shutdown/ restart/ log off, and do lots more on your Windows PC remotely via your Twitter account.
The latest version, TweetMyPC 2.0, has lots of new features compared to the earlier version including Screenshot, Memory usage, IP address, Custom commands, Reply from TweetMyPC, and several others.
The application has earned rave reviews, being featured on popular technology blogs like Lifehacker, Makeuseof, and Gizmodo, and has had close to 9000 downloads on Codeplex. Sara Ford, a Program Manager at Microsoft, even featured the application at TechEd US in her session on Codeplex.
The application is available, with source code, here: http://tweetmypc.codeplex.com/.
via http://blogs.technet.com/southasiamvp/archive/2009/09/26/be-a-pc-ninja-using-twitter.aspx