Daylon Graphics - Leveller - Tutorial hosted by the creator of the program Leveller explains how to create a vegetated landscape scene using the Leveller heightfield editor and POV-Ray.
Ib Rasmussen's - Mini tutorial on the use of POV-Rays built-in wood textures.
The Online POV-Ray Tutorial - Excellent resource for POV-Ray users, from novice to expert. It is well designed and documented.
Persistence of Text - Great introductory material on POV-Ray including information for Macintosh users
POV Ray Tips - Many useful tips, tricks and techniques for POV-Ray.
Rune's Blob Tutorial - Tutorial explains how the threshold, the strength, and the radius values in blobs work, and a few tips are given that can make it easier to work with blobs in POV-Ray.