Commercial expensive semi-crap solutions
rough IR computer interface circuits

This page indicates that most transceiver chips operate at around 34-42KHzo

small circuit to attach an IR LED to the serial port and read and write bytes-as-bits at 38.4KHz

lots of technical info on remote control protocols and speeds


(halleleuia!) linux infrared remote control drivers, along with a trivial transmitter, and support for many many receivers (including my logitech/ast one)