The guys at HardwareSecrets have posted a handy guide to making an IR transmitter for your PC for connectivity to devices like your cell phone (if you haven't got bluetooth on it, anyhow). I can remember when almost all new PC's came with IR receivers....

"Several motherboards have the necessary hardware for the installation of an infrared transmitter/receiver, requiring only the installation of a module containing the infrared sensor. The great problem, however, is that this module is not easily found in the market and, when it is, its price is high."