I've had success with using rings or 'clamping' too.
I've increased half an inch midshaft girth by edging to orgasm for about 30 mins per day with a Cable Clamp brand clip around the base of my penis. I'm 21 years old with an athletic build, and have managed to get my girth to about 6.2 inches!
It started out as pure curiosity after reading a certain penis enlargement forum (which I suspected to be bullshit). But after nearly 10 months of doing this, i've seen some real gains.
Plus, stroking your cock for half an hour each day can hardly be called a chore

(unlike some of these exercises for length gains involving hanging weights off your willy, or repetitious stretching motions).
In short - I agree!