Don't know how many of you know who Mike Masse is,but check him out on youtube.Basically hes a guy with a great voice and a nice acoustic guitar who duets with a bass player and they do acoustic/bass versions of many great songs.
Well me and our guitarist do a similar thing though not quite the same calibre as Mike.Last night we were doing our version of 'Africa' by Toto,(again,inspired by Mike Masse) when,in the chorus, where me and Paul, the guitarist, launch into a strong 2-piece harmony,a guy in the crowd stood up and launched into a 3rd harmony,and continued to do so throughout the song.We play quietly usually,so the guy didnt really need a mike.Suffice to say,its always good when somebody in the crowd reacts to what you're doing in a positive way.