Controlling the PC using Mobile Phone from Very Very Remote Location
Its an Interesting project topic. All you need is a mobile phone with the facility to send and receive email as SMS.

The remote PC will have an email client with an email command parser. The email client that written in JAVA or .NET will check for new emails in a particular time period. If it received an email from your account it will parse and executethe your command.

You have to send the commands in a predefined package like

#suhtdown
#reboot
#filelist <path>
etc.

The shutdown and reboot functions can be executed using the operating system API's