iPad Drawing App Recommendations?

I suppose this is only indirectly related to picture generation, but I am not sure where this goes. I have my iPad, I have my stylus, but I am not fully satisfied with the app I am currently using for drawing. Anyone have any recommendations for good drawing/painting apps for the iPad? I have an iPad 2.

I have two use cases - one for iPad digital art, and one for quick sketches. It would be ideal if I could get just one app for these, but if not, then separate ones are fine.

For digital art, I would prefer if it was an app that had a variety of brushes, filters, etc. and the ability to handle more than six layers. For quick doodles, I mainly just want it to be fast, and easy to use.

As for cost, I would prefer something under $10, but if you do have something over that price, I might consider it, especially if there is a free or lite version I could play around with.

Thanks.

for quick sketches, I would recommend Sketcbook. Even the free version has a lot of different brushes to choose from. I doodle on it when I'm bored, and it creates some good quality sketches. The pro version ($4.99) says it uses 12 layers on iPad 2.

here's the free (express) version: http://itunes.apple.com/us/app/sketchbook-express/id410871280?mt=8

and the paid version: http://itunes.apple.com/us/app/sketchbook-pro-for-ipad/id364253478?mt=8

Thank you! I guess they changed the pro version to use only 4 layers, but this app basically has everything else I wanted. :-)