Chuey himself used to bring his caps (made from up-cycled thrift shop wool coats and such, I believe) into the Missing Link in Berkeley. I have three that have the extra pulldown jersey/knit to cover your ears. They fit nicely under helmets, give you a visor for winter rides when the sun is low, and the knit section takes the chill (and the whistle) off your ears. I'd buy more if I could. On the minus side, the sizing tended to vary like crazy from cap to cap, so I don't think it would have been safe to buy outside of a store where you could try 'em on for fit first.

Do an image search for Chuey Brand cycling caps and you'll find them (my Bike Forums account doesn't let me post images or URLs).

Chuey's website looks like it's been inactive since 2015, but it's still there.