ChickenToonLighting
As with the basic lighting effects, I've spent a lot of time in the past making YouTube videos about toon shaders in GameMaker. Such information is pretty useful to have. (In particular, writing your own toon shaders is a good way around the $5 price tag if you don't feel like paying.)
These, of course, build off of a long line of other shader videos I've done in the past. This is not entry-level stuff.
The first video was made by someone else, and is a FANTASTIC primer on how toon shaders work.
The other ones in this list were made by me.
