For a transmitter/reciever, I use the USB UIRT (google for it.) It is directly plug and play with the rest of the system, and can recognise the MCE remotes out of the box. It also makes an excellent IR blaster to control your AV gear.
I also use a Nokia 770, the touch panel of my Cisco 7970, and my Nokia N70 mobile phone as orbiters for the house.
-Thom