A couple of weeks ago I had a unique opportunity to attend one of Amanda Palmer's ninja gigs. If you've not heard of them they're rare-ish but growing in notoriety. Basically, she and whomever she's on tour with at the time roll into town and get in touch with a promoter, a theatre, a nightclub, wherever they can to stage a two to four hour rehearsal/mini-concert/bull session with no cover charge. They're often held the night before their full-scale concert though it wouldn't surprise me if there had been an exception or two. Whoever wants to attend …