I host an open mic night here in a donation based cafe inBanbury and we get a wide range of performers. So far we have had a didgeridoo player, a banjo player, flamenco, poetry, people doing songs from the musicals and even a lady playing the Doctor Who theme on a saw. Itnis always a welcoming atmosphere with no one judging anyone. I know of at least 3 guys who made their live debuts with us and now regularly gig for cash. Is it exploiting musicians to play for free? Thats your judgement but from my experience, just being somewhere that is a conduit for expression ina a warm and friendly atmosphere is worth it.