I had no idea how much I needed this plugin until i got it. I had 2 divs that wouldn't line up right no matter what I tried. Installed this extension, turned on outlines, and figured it out in 2 secs. Lots of other great tools included too!
I'll have to look into the licensing to see if this is open source, but either way it's a slick little music player. We'll be using this for the podcast soon.