I've heard tell how difficult Ansel Adams' Zone System can be to understand and absorb. Here's another method for determining the proper exposure of a particular scene: The Posograph. While as it is perfect for amateur and professional photographers alike, it is very clearly intended only for those with exceptional eyesight. Which makes it elitist and therefore, cool--just like the Zone System!, only for the young.
Curiously, it hasn't caught on. I reckon it most likely because it doesn't yet have a celebrity photographer touting it.
Now that we've absorbed that and we're all out making images: Who hasn't had the following problem? And all for the lack of the proper face cream...
A tip of the hat to David for these wonderful photographic artifacts.