Not long ago I happened to stumble upon this great little piece of software.

MyPaint -> [link]

Basically it's a painter like so many others, yet this one combines a lot of nice features:

    * Unlimited canvas (you never have to resize) (!!!)
    * Fully customisable dynamic brushes
    * Support for pressure sensitive graphic tablets ( Of course )
    * Small, fast and lightweight.
    * Cross-platform ( Windows and Linux .. maybe even Mac in time )

Furthermore full support for layers is expected in the next release which hopefully will be out very soon.

The best thing about this piece of software is of course that it is open source.
If you've got any cool ideas for the interface, features, functionality, etc. you are encouraged to submit them to the developers. Then if you're lucky your ideas might be included in the very next release !!

So if you're up for trying something new check the website and please give your opinion:
[link]

A note worthy detail is that the developer of this program is in fact a deviantArt user.
Say hello Martin at: ~Matumio

PS: Don't get scared away by the screenshots on the site thought.
They're old and the program does look better. Plus the interface ( especially the color selector ) is being reworked.

I'll post some screenies later