I'm the main developper of BlackInk a new drawing Software currently in private Beta test.
Black Ink is a drawing software that uses the features of your graphic card for rendering extremely smooth, even on very high definition.
Thanks to Virtual Texture update the user can draw in 10Kx10K image without any lag.
Black Ink does not try imitate real graphic, thus it may also register as a generative art software.
For example, Black Ink does not seek to imitate watercolor or oil painting, but takes advantage of your computer to provide tools that do not exist in reality.
You can check some creations done with it at http://blackink-drawing.tumblr.com/
The Public Beta will be released soon at http://www.bleank.com/
Technical blog http://u2bleank.tumblr.com/