To the original list I'd add Zefal Dooback mirrors (left & right) that work well on folders.

On my main bike, I actually have a humongous mirror attached to the basket, whose original function was to show the aisle to flight attendants in some of the Boeing planes. Regarding the eyeglass/helmet mirrors, like another poster I am allergic to sharp objects sticking out next to my eyes. Also, I want my mirror to remain functional during rain, when I put a cover on my helmet. Along the same line, the mentioned bike-eye will not work with a rain cape or even a coat.