have you looked at streampad.com?

here’s the firefox smartlet (%s is replaced with URL), use with any page with mp3 links:

http://www.streampad.com/flash/playerL.swf?autostart=yes&list=%s&songNumber=0

two things that i like about streampad is that it also gives you a dynamic RSS for the page, and you can have it display and play your mp3locker files (from mp3tunes.com). i think it’s better than webjay.