what you gone give for users? mp3 for download (remember licences), your own mp3's or just a possibility to listen for music (without downloading)?
Express your site, tell me more what is your idea and maybe i'll show you the way
i have few scripts that playback mp3's: few of them are in flash, and one of them are in php (you can do a a streamcast server only with php, no aditional software is required) so if you will need this scriptts, PM me and i share script's/link's