Mathias Panzenböck, a programmer in Vienna, has been working quite a long time on a Web 2.0 style audio player for Magnatune. It works in pretty much all contemporary web browsers, despite the very fancy HTML5 features he uses.
His audio player is now very feature complete, and I'd like to recommend you give it a try at:
Mathias calls it the "Greattune Player" (because "magna" means "great" in latin) and with it, you can:
1) browse albums by genre
2) drag and drop songs into playlists
3) as a member, download albums in any format
4) drag recommendations to your playlists, to listen to them later
5) export your playlists into files (even as html web pages you can put on your web site) that will play in most any music program
6) view artist bios, album art, embed the album in your blog, and more...
In short, pretty much everything you can do on the Magnatune web site, you can do with the "Greattune player", except that you can do it with Web 2.0/HTML5 goodness.
I've placed an icon on the magnatune home page so you can easily jump to the "Greattune player". You'll find it toward the bottom left of the page:
Below are some screen pictures of the player in action, showing me playing and browsing, modifying my playlist, and exporting my playlist as well.