Admittedly not very unsung, but I just can't withhold this broadcast from you; it's the most painful, and therefore funniest thing I've ever experienced in the field of orchestral "playing"... (b.t.w., the playing starts I think at 2:30 or something, after a lengthy introduction) Enjoy!
http://www.youtube.com/watch?v=xzPxObs2NtQ&feature=related
Marvellous! Does anybody remember the Portsmouth Sinfonia (1970-79)? Now they really put the 'sin' in 'sinfonia'! If you have a strong stomach and some spare underwear you might like to try this:
http://www.youtube.com/watch?v=hpJ6anurfuw
or, better still, this:
http://www.youtube.com/watch?v=-wiRivDMIYM&NR=1
And for all those who still treasure their 1980s 'Hooked on Classics' LPs, there's always this:
http://www.youtube.com/watch?v=FgKDKyl-EKE&feature=related