The perfect antidote to Wikipedia: Uncyclopedia — “The content-free encyclopedia that anyone can edit.” Seems to suffer some performance problems, but often worth the wait. From the Air Guitar entry, which comes complete with annotated air guitar diagram:
Air guitars are similar in shape to normal guitars, with the notable difference that they are made entirely out of air. Air guitars typically have 6 strings and 24 frets. Although acoustic air guitars are available, electric air guitars are by far the most popular.
One perspective: Way too many people have way too much time on their hands.
Another: Thank God for that!