Exercise Your Music Muscle

(Click image to view full size)

Check out this cool picture - it's a new advert of sorts (Part of some "exercise of your music muscle" idea) from Virgin Digital. Apparently there are 75 74 bands/artists represented in the image.

How many can you spot?

Update: I've just realised the image is missing about an inch from the left. Here's the picture with this extra inch "glued on".

Update: The answers.