Another letter of the alphabet - this time O for Octopus. (B was posted earlier.) I guess I was thinking of old Mary Blair illustrations and vintage Golden Books when I did this. Done all in Photoshop, I made the textures by making a custom brush. I started with a Spatter Brush (my favorite brush, and it's in the default palette.) Then I adjusted the spacing and played around with the jitter stuff and you get a brush that has a kind of chalky dry brush effect.
Here's a close-up of the effect. This ended up being a super fast way to do some shading. I had a lot of fun coloring this.