Uzu is an awesome particle-based app. It can create wonderful kaleidoscopes and pinwheels. It is jam-packed with functions that are probably a bit too advanced for me and other non-scientist types, but that doesn’t minimize the fun had creating imagery with it. I just have to study it and use it more.
Some of the lines it is capable of creating are so fine it is like playing with fur. And the colors! Some particle-based apps seem a bit stuck on RGB without much finessing of all the tones, shades, tints, secondary and tertiary color nuances, but not Uzu. Apricots, orangey-pinks and greys can easily be achieved.