I know its already been suggested so don't flame me for reposting.
But I figured out how to do the drive space slider to give folks what they want and it is so simple I don't know why I didn't think of it sooner.
Just reverse the logic, instead of expanding left to right to display drive used space, expand right to left to display free space and use the "darker" image for the slider and the "lighter" image underneath.
This way if someone wants to use a picture in the theme, the drive space frame will contain the picture instead of a grayed out frame, and the drive space slider will cover up the free space.
Hopefully this is simple enough it will make it into the 1.1 release.
Well from my research on google, I couldn't find an easy way to make the image expand from right to left
But I figured it out anyway,
Check the contact email for the site, I sent you the code change if you want to use it.