Wiki Tutorials for the Gimp
This might eventually become a collection of tutorials entirely written inside this wiki. If any other wiki tutorials sites for gimp are out in the net, this one might become superfluous 
The Tutorials
Basics/Layers: The basics of layers and layer masks
Basics/ToolSize: Being able to change the size of your tool up and down with keys
Tutorials/HighlightColor: Change the color of highlights
Tutorials/ChangeProfilePath: Change the Gimp's folder to another location.
Tutorials/AddAVignette: Adding a Vignette
Tutorials/InstallingFocusBlur: Installing the Focus Blur plugin
Tutorials/Horizons: Getting a horizon level
Tutorials/HazeRemoval: Removing atmosphere haze
Tutorials/ToneMapping: Reduce global contrast while increasing local contrast and shadow/highlight detail.
Tutorials/SplitToning: Change the hightlights to one colour and the shadows to another.
Tutorials/BurntParchment: (can anyone migrate a photoshop tutorial?)
Tutorials/SimpleTextOutline: Creating outline text
Note: It might be useful to be able to either upload images (dunno about disc space/ traffic volume) or to link to external images which shouldn't be dependant on the filename extension...