Viralata has written two tutorials on his site using some of the new features of Blender 2.43 to achieve nice toon and sketch styled renderings. Are you tired of doing the same old photorealistic rendering? Try this out!
The tutorials guides you through this style of Non Photorealistic Rendering (known as NPR) step by step, ending up with good results that replicate hand drawn work quite well.
It's certainly worth learning this and adding it to your toolbox of techniques. Being able to do some NPR is always a good thing.