Something I didn't know but discovered by accident not long ago. I was using UV light to cure resin on a project a few weeks back and I was looking away while doing it... a bright yellow/green piece of wood caught my eyes far away in the shop... sure enough, a piece of black locust burl
Cool. Although I have never actually seen it done before, the online Wood Database has an article and data table for using UV fluorescence to aid in identification of unknown wood species.