Krita is part of the Calligra suite, KDE’s set of office programs, and is quite unique among open source applications. Where as something like GIMP is an image editor and processor, Krita specialises in digital painting. This kind of tool is much sought after these days by many artists who prefer to create their works completely digitally.
The latest version of Krita has just been released, and adds some excellent new features. First up is Krita Gemini, a way to move seamlessly between a touch-centric interface and a traditional desktop set-up. Many artists like to use Cintiq touch-screen monitors, which makes this ideal. Support for tablets has been improved, a pseudo-infinite canvas has been added and there are many other interface and painting tool upgrades that make the entire package just that little bit better.
Grab the latest version of Krita from the official website, and maybe even introduce it to a friend on Windows.