Thanks to Cali Lewis on GeekBrief.tv for mentioning an application that I just had to go and check out once i saw it.
Livebrush is another free paint package, that should work well on an IWB. The size of the brush stroke depends on the speed you drag across the page, the faster you go the broader the brush stroke.
It runs on the Adobe Air platform, so if you can run applications like Tweetdeck then you should be able to run this no problem. Some school networks might block this though, so check if it’s OK to install.
It’s free, but there is a “pro” version for only $10 that gives some extra features. Check out Livebrush now.
I love these kind of applications. If you want more IWB tools for Art then check out my links on delicious at: http://delicious.com/dannynic/art+iwb