Art Rage is a great art program that mimics the appearance of real paint, chalk, colored pencils, crayons, etc. The texture is impressively realistic. Art Rage offers a free version, which is enough to keep almost any teacher happy. If you want even more features, there are higher-end versions available at varying price points. I first learned about Art Rage from Tom Barrett's slideshow about Interesting Ways to Use Your Interactive White Board. Interesting way #16 recommends using a (clean) paintbrush along with your Smart Board. My students have really enjoyed this program, and frequently ask to play with it if we have a few extra minutes at the end of class.
Note: I highly recommend visiting Tom Barrett's blog for a ton of information on numerous topics, including technology-based projects. Also, he's been kind enough to include some of my ideas in his slideshows. E-mail him with ideas that you are using in your classroom, and you might show up in his slideshow, too!
Dr. Jessica Pilgreen, Ed.D.