Firstly, I absolutely love the W3TC plugin and appreciate all the work that's already gone into it.
One feature I'd love to see implemented is a quick and easy to get get CSS Sprites working. I mention this because W3TC does an excellent job boosting the YSlow score with caching / cdn capabilities and the ONE thing it's lacking on the YSlow charts is CSS Sprites. If this plugin had a quick and easy way to get Css sprites working, it would be the ultimate all in one solution for speed because it would, by itself, get an A Score on YSlow.
Is there anyway I can donate towards W3TC development? Last I checked there wasn't an option to do so, but I absolutely love this plugin and have used it for quite a while now.