This tutorials shows how paths, selections and channels work in one single project. http://www.simmerspaintshop.com/forums/gimp/1084-paths-selections-chan...
Here you can read how to download, compile and run the newest development version of the GIMP http://www.gimpusers.com/tutorials/compile-gimp23-with-ubuntu.html
GIMP 2.4 comes with brand new tools, a better user interface and lots of cool other stuff. http://www.gimpusers.com/tutorials/gimp-2-4-new-features.html
This tutorial will teach you how to make a nice avatar using Gimp, that you can upload for use on online forums, message boards e.t.c. http://www.tutorialsworld.com/index.php?option=com_content&task=view&i...
This is a short tutorial that shows how you can easily create an effect like a swirl like you see them on spinners on aircraft. http://www.simmerspaintshop.com/forums/gimp/1382-making-prop-swirls-gi...
Layers offer you great possabilities to work. You just need to understand how they work and what tricks you can do with them http://www.simmerspaintshop.com/forums/gimp/512-using-manipulating-lay...