I feel obligated to post this webcomic.
Manly Men Doing Manly Things
But besides that, The New Encyclopedia of Modern Bodybuilding : The Bible of Bodybuilding, Fully Updated and Revised [Paperback] by Arnold Schwarzenegger has a lot of great visual references for extremely muscly men. It is a book about bodybuilding, but it has way more pictures than you might get in an art-geared book, and a little cheaper.