MyPaint is an easy-to-use, open-source digital painting application.
Open the program and you'll see little beyond a blank screen, colour selector and wide range of brushes, then. The latter start with the familiar - "pencil", "pen", "marker", "watercolour", "sponge" - but soon branch out, with realistic oil, pencil or charcoal, and move on to the experimental "fur", "leaves", "DNA-brush" and more.
If that's not enough for you then you can tweak the built-in brush engine to produce new styles of your own.
And support for pressure-sensitive graphics tablets then helps you produce quality artwork with minimal effort.
The program also includes basic layers support, which means once you've created a background then you can begin to paint above it, without affecting once you've done before. And if you make a mistake at some point, of course there's an unlimited Undo option to reverse the most recent changes you've made.
The end result is an interesting and powerful package; if you've the talent, then MyPaint can help to bring it out. And for proof, look no further than the program's Galleries, which have some great examples of artwork produced with MyPaint.
MyPaint provides the tools you need to create great works of art (although you will still need some artistic talent to apply them, unfortunately)