Topic: skinnable divs

It occurs to me that many people have one version or another of skinnable div's:  images for:
* top edge, top left corner, top right corner
* bottom edge, bottom left corner, bottom right corner
* left edge, right edge

something like that. 

I'm wondering if there is anyone knows of / implemented something reasonably generic that can be adapted across a whole website, without re-implementing the CSS itself.  I actually just plugged in a prototype based "windows" module:

They essentially already have skinnable windows, so I could probably just base my own more generic skinnable div's off of what they have (meaning implementing something like what they are doing, but not just for these floating-div windows).  Just curious if anyone has something like this, and how elaborate it is.