Really Cool Drawing Site

While reading Mini Matisse's Blog I learned about this really cool online drawing program that allows you to draw with different types of marks:  fur, webbed, squares, ribbon, sketchy and others.  I'm in love with how it looks!  I have an idea to draw using this program, then print them out, add color with paints or colored pencils and then incorporate them into a mixed media collage. The only thing I don't like about it is that it appears once you've made a mistake you can't click "undo".  Clicking "clear" will clear the whole thing.  Maybe I'm not figuring something out right?  The drawing program is called Harmony and here are some examples.