We do something similar, but vastly more evil, with Compass on our product. We need the visual experience to be solid on IE (our customer base is enterprise). So... we generate and cache PNG's with ImageMagick using hooks we wrote into Sass. For instance, we can specify arbitrary gradients using Sass color variables and direction/distance arguments, auto-gen rounded corners, and in some cases render text using non-browser-safe type.<p>I wouldn't recommend the approach (I think it's going to be incredibly clunky in a year or so, and that things like Fancy Buttons that use Compass to hide the complexity of optimal degrading CSS are the way to go), but it is an example of how flexible Compass and Sass are: you can abuse them terribly, and they'll stay loyal.