WinLIRC is a software application that enables users to control their computer from a remote location. It allows users to remotely control their computer's applications, media players, and other functions over the internet. It is compatible with Windows, Linux, and Mac OS X. It works by using infrared (IR) signals to transmit commands between a remote computer and the computer being controlled. The application can be used to control media applications such as Windows Media Player, iTunes, and Winamp, as well as other applications such as web browsers, system configuration tools, and more. WinLIRC also supports the use of game controllers. The application supports multiple languages and can be used to create custom scripts for automation purposes.
EventGhost
Remote Buddy
LIRC
It does much more than WinLIRC, although it lacks as much support for IR modules. Much easier to use, even for semi-complex tasks. Can run your whole house, and is open source. Excellent support in their forums. Absolutely worth a good look.