I'm new to this stuff. I just signed on last week. I'm impressed with the stuff I've seen so far. My gallery photo is a chalk drawing I did on the driveway. That's what driveway's are for, right. I make my own chalk. Let me give you the recipe:

Get a long empty cardboard tube such as an empty wrapping paper or even toilet paper tube.
Get a back of plaster of paris from an art supply store.
Add some powder temper paint with the plaster and add some water.
Stir.
Set for about 24 hours.

You'll have delightful chalk. Don't be too skimpy on the water. I've done that. It'll make the chalk too hard and it won't work.