I've only very recently discovered the "Bike Forum" and ran across this thread and wanted to add my $.02. I ride a Burley Canto and all my riding is by myself so I wanted some accompanyment. I started out with a BYCOS stereo system. These can be found at
www.bicyclestereo.com. What this is is a amplifier and speaker system to which you have to add your own radio / CD player. The amp mounts in place of a water bottle cage. I mounted the amp on the handle bar post and mounted the speakers on the handle bars near the brakes levers. I eventually replaced the speakers with Radio Skack CB speakers #19-318A. I made my own speaker mounting brackets and in turn attached the assembly to the handle bars with Minoura mounts. I haul my bike with a Draftmaster rack and I did not trust the plastic brackets which came with the Radio Shack speakers. While the sound is not home theater quality, it's just fine for me!
Thanks,
Garry