TITLE: A nice book on representation of groups (not too theoretical, for physisicts purposes)
QUESTION [5 upvotes]: I am looking for an easy to read book on representation theory. I learned some basics in group theory, differential geometry and lie algebra and I need to understand the representation of continous group. 
But I am more a physicist than a mathematician so I would like a not "too theoretical" book in math but something too understand the structure and the notions.
To give you an idea I want to learn this to understand the usage of representations in quantum field theory (so it is really for physical purposes).

I appreciated a lot all the answers but does it exist books with corrected exercises inside ? I am looking for exercices that check the comprehension of the chapter rather than "hard" ones. I forgot to ask it in the beginning.
I know I am quite demanding but it would be really nice =)

REPLY [5 votes]: Peter Woit: Quantum Theory, Groups and Representations: An Introduction
My hope is that this level of presentation will simultaneously be useful to mathematics students trying to learn something about both quantum mechanics and Lie groups and their representations, as well as to physics students who already have seen some quantum mechanics, but would like to know more about the mathematics underlying the subject, especially that relevant to exploiting symmetry principles.