Learn how to build an infrared transmitter/receiver for your PC, in order to connect IR devices to it, like cell phones.
"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. In this tutorial we will show you how to build this module spending barely nothing. Any user who knows how to use a solder iron can assemble it."