From Hoxton, through Shoreditch down and across to Brick lane there are hundreds.
If you where to go to Brick Lane/ Spittlefields, (just right of the City E1 and E2 post codes. Both easily walkable from Liverpool street station) have a little search, pick up fliers etc you'd find twenty or so within that area alone.
A very interesting area for contemporary funky art in general, and a good taste of real London and its people.