If you like GIMP you will probably like the new version even more. And for those who are not familiar with GIMP in short:
GIMP is a free (open source) alternative to professional image manipulating programs such as Adobe Photoshop. For the amount of money ($0), you get quite a package and you can do most of the things you would be able to do in professional programs, and in some cases even more.
The new 2.8.0 version, comes with yummy new features like, Single-Window Mode, Multi-Column Dock Windows, Layer Groups and numerous of other interface and tool upgrades. Click here for more info.