What was intended as a simple bit of self-effacing humor from actor William Shatner has instead become a challenge laid at the feet of the creators of Shatner's Toupee -- a blog devoted entirely to the question of Shatner's hair (or lack thereof). They provide the web's most detailed movie-by-movie analysis from Shatner's filmography on his various rugs.
The amazing thing is how serious (and thoroughly researched) the blog is in its quest for an answer. It makes the whole thing funnier somehow (which I'm sure is intentional) to read someone poring over every frame of some long-forgotten Shatner television appearance for indisputable proof, offering a play-by-play opinion of every head scratch, every combed part, and every hairline that's found its way onto the actor's head. While Shatner himself has never owned up to any wig-wearing, Shatner's Toupee makes a pretty convincing argument otherwise.
(Special thanks to my friend Micah with Reel Distraction)