Just one i thought of just then, if you're going to do finger painting. Get some toy cars and use their wheels through the paint- makes a fun pattern
- egg yolk with some food colouring in it looks beautiful when it dries
- put some drops of paint on a piece of paper in a tray (with sides) and roll marbles/balls etc around in it so the marbles/balls roll thru the paint and make patterns
- brush a flyswatter with paint and slap it onto a piece of paper
thats all i can think of off the top of my head...but you sure did get me a-thinking