I've added a Flash MP3 player to the site. You can use it by putting [mp3][/mp3] around a URL pointing to an MP3 file. To use it you need somewhere to host the file.
Before someone asks: Yes we are still working on adding music uploads to the site, and it's going to be great once released. But we decided this was a good feature to as while you're waiting for that. Report any bugs here.
I suggest our newly created constructive criticism forum if you want to try out the the mp3 tag.