>>26
I'm using Paint.NET, which has everything you just described except the distort filters (without downloading add-ons, I guess). I still need to study up on how the different blending modes actually work.
I've been messing around with the different settings, especially since some methods work better on certain art styles than others do. Cartoonish fluids can look acceptable, as long as the rest of the picture is cartoonish as well.