See, it even looks dumb in the Amazon ad! What is that, a black rectangle? Sweet, I'll totally drop thirteen bucks and change on that.
What you're actually seeing is a simple tube of thin, wicking polyester fabric, available in about a zillion colors/patterns, designed to be worn about the head/neck/face region. I was introduced to these things by pal and frequent blog-commenter Steve K. of Peoria after I'd lamented about my increasingly Pantani-esque melon and its vulnerability to STHVS: Sunburn Through Helmet Vent Syndrome. Steve said, in effect, "Get ye a Buff, oh chrome-domed one," and although I was initially skeptical, I did.
Lest you think I'm underdescribing the Buff, it really is just a fabric tube. Hot day? Pull one end over your dome, let the other hang down the back of your head covering your neck, and ride off happy. If it starts to feel sweat-soaked, swap the ends -- the one flapping around outside your helmet is probably dry. Slightly cooler weather? Double it back on itself and pull it down far enough to cover your ears. Either way, it's thin enough to fit under a helmet without even adjusting the straps. Oh, and just in case you need a snazzy cravat for a post-ride cocktail party, pull it down around your neck and schmooze away, Mr. Fancy-Pants!
I should have some downsides here to give a veneer of critical balance, but I got nuthin. The Buff has one fairly simple job to do and does it well. I would say that it makes me look like a dork, but it's not really fair to blame the Buff for that particular pre-existing condition.