So Ive been playing around with a new program called Krita. It has a really neat brush engine. And its free lol. Ive actually been using it more then Sai lately, though SAI still wins on certain tools. (paintbrush blending is much better in SAI)

Shirts and prints available:
http://www.redbubble.com/people/ectoimp/works/23089742-bat-sketchy?asc=u&ref=recent-owner