What follows are web links on GIMP.
- User Manual for GIMP 2 - available online in several languages. The manual is licensed under GNU FDL 1.2 or any later version.
- Grokking the GIMP - a book available online under the Open Publication License. Also available in print. Written for GIMP version 1.2, it is still a good resource.
- Wikimedia Commons has videos showing some uses of the Gimp (without sound).
- YouTube also now has plenty of GIMP video tutorials, such as this one.