I run a monthly night at a small licensed art cafe. The way we work is we have a featured artist who does a hald hour set first (usually a solo acoustic), then 10 min open mic slots allotted to ever wanys them then an open jam. I provide back line, a bass, acoustic and electric guitar etc and encourage anyone to have a go. We had one guy who was passing who popped in, bought a beer, asked if knew Key to the Highway, sang it like Howling Wolf as I busked it on acoustic, drained his beer, shook my hand and then disappeared.