Congrats on an excellent add in - trying it out at the moment. Was considering integrating minification combination of js and css into MSBuild until I came across this and this does something very similar.
Wonder though if it would be possible to integrate in the conversion of images in css into a base64 string, resulting in less http requests. I believe only IE8+ supports such so it would need to an optional feature, ie. create a css with the conversion and
a css without. A demo of what I mean in the following video -> http://madskristensen.net/post/Embed-images-in-stylesheets.aspx
Any thoughts on this? Just another area in which this add in could help improve the performance of css.