Something I've been messing with:
You'll have to go here to see the real one. Enjoy!
(roll the cursor around to see the tooltips that should guide you in the right direction).
Update: I've cleaned up a couple of small things in the design. The app is still too heavy, and future iterations will have to be much lighter and faster.
Update 2 and 3: Updated the engine to the XSPF standard, added a load-progress bar, help text, credits, and included a rollover to XML provided ID if ID3 isn't available. Later: changed the division key to a "help" key.
Some notes: yep, this is not a design that allows for intuitive use. (Where's the "play" button? How do I make it go?) This is not a design I'd spring upon an unwary populace, but it's fun - and as an exercise for me, it's perfect. And the buttons are be skinned dynamically.. just drop them into a folder with the correct filenames and they will appear on the calc at runtime! So changing the "=" button to look like a "play" button at rollover is eaaaaasy....
Update 4: Whoa! This is featured on the scale nine frontpage! Thanks, Juan!
(and re-positioned this post to the top of the blog)