Generally I’m not a big fan of music playing in the background of a web site. You just never know if the visitor might be sneaking a peek during a staff meeting or having a sleeping child nearby.
But sometimes music can be fun. Recently I created a fun online holiday card for a resort and we used some music in the background. To do it, I had to find royalty free music and I thought I’d share the site:
We used a clip from this Christmas site: http://feelslikechristmas.com It was free.
For a wide range of music: http://incompetech.com/m/c/royalty-free The music is free, a donation of $5 is suggested, which is darned close to free.
Another good range, of fee-based music: http://www.musicbakery.com
Byte of the Week 
I don’t know why but it feels like the feelslikechristmas site is trying to use artist to contribute their songs for free so that lots of people can visit their site and they can make money of ads and adwords. One thing though, I don’t like artist contributing for free anonymously as you don’t know a few months or years down the line if the terms of the use of the music is still royalty free. Also it does not say it is royalty free anywhere. Maybe you can only download to hear it but it does say greeting cards so may be it is creative common license.
Hi,
I am writing in from http://www.opuzz.com/. We have a good royalty free library that is worth checking out.
Thanks