SuperKaramba is, in simple terms, a tool that allows you to easily
create interactive eye-candy on your KDE desktop. Currently, only Linux
is officially supported.  

How does it work?  
Theme writers create themes, or text files that define their widget.
Then they can optionally add python scripting to make their widget
interactive. The possibilities are endless!   

Here are just some examples of the things that can be done:  
Display system information such as CPU Usage, MP3 playing, etc.  
Create cool custom toolbars that work any way imaginable