For a little side project, I'm using jPlayer, a nice jQuery-based audio player.   I wanted to skin the buttons a to suit my project, and while jPlayer does support jQuery ThemeRoller skins, I liked the basic look and feel of the standard jPlayer controls.  So, I just traced the default sprites in Illustrator in order to recolor them.  For other jPlayer developers, you can download the source SVG  here, and tweak away.