Another one is VB-Amp. It can be found at http://www.ryerson.ca/~sgray It is written in VB, and you can get the source and play with it.

Some of the nice features are:
Complete skinning ability (you can locate buttons anywhere you want),
Transparent skin (rounded corners, holes through the skin, etc.),
A visual playlist selector (gives you 4x4 thumbnails of album covers/playlist pictures)
Plays any format Windows Media Player does (uses this as an engine), including mpg, etc.

Lots of other features, and it's pretty stable. Of course, being a VB programmer, I am biased because I can make of it what I want.

I used this program for my homemade in-car mp3 player, but never managed to get a screen in the car to view it with. I figured it'd be cool to flick through album covers until I got to the one I wanted, and then to invoke geiss as a visualization. Then I realized that the hospital would be a boring place to stay after paying more attention to geiss than the road, so it never happened.

-Trevor