Good Style Shop is one of the more awesome used clothing stores in Madison. I've been in there once to shop and once to see bands. Both experiences were great.
The shop's selection is geared towards utility over kitsch, and it isn't hard to find awesome stuff. I snagged a vintage Badgers sweatshirt and a Red Dog beer shirt (a true gem). The owner, Pete, is a great dude, as are the workers. All were very pleasant and didn't hesitate to say hi/introduce themselves.
The shop is organized nicely and, while it does gravitate towards women's stuff, there's plenty for both genders. I'd recommend Good Style Shop to anyone looking for a fun thrifting experience in Madison!