My brother plays violin in a rather nifty quintet called Tango5, which specialises in the music of Astor Piazzolla, the Argentinian composer, bandoneon player and Tango master. They have upcoming dates:

2010 27th April, Peel Hall, Salford.
2010 29th April, Beverley, East Yorkshire. More info.
2010 1st May, The Forge, Camden.