Comment C.C.Crane (Score 4, Informative) 438
My S.O. and I are KCRW.com freaks. We also have FM radios throughout the house, along with the living room stereo system - where my S.O.'s PC also lives. I split the audio line from her PC: one line goes to the living room stereo, the other goes to a cheap C.C.Crane FM transmitter. This is the absolute cheapest way to get a single source of audio (CDs, MP3 library, streaming audio) into every room of the house. Note: the FM signal strength from the Crane transmitter sucked at first - then I found a web page that showed how you can open up the Crane transmitter and tweak the signal strength to maximum. Works great now.