Hello! I'm a beginner with Processing (though I've done quite a bit of graphics and game programming in C, C++ and shaders in GLSL and Cg before, and Processing doesn't seem very different so far, so it was easy to get into).

I wrote a little Processing sketch that allows you to draw with a brush that generates particles that follow brownian motion and leave trails, creating an interesting effect. You can play with it online (uses processing.js).

I also modified it to read in images and paint them, here are some results (last few pictures in the album).

Also a long while ago when I dabbled in Processing a little bit (didn't do much though back then) I made a little animation for my dad on his birthday.