Hey, y'all, I made some new buttons to use with mp3-jplayer, and thought others might find the file useful, so I posted it on DeviantArt.
It's a Photoshop file; to change the colors for the hover state, just replace the fill colors on the shape layers to whatever you want them to be. I put the image files in my theme directory and changed the path to them in the custom CSS file I'm using.
There's a hidden layer with embossed button backgrounds on it; they didn't work for me without futzing with paddings and such for the buttons, so I turned them off, but in case anyone wants to use them, I left them in there.
The original buttons are on the bottom layer, so you can see how the new buttons line up with the old ones.