These windows invite you in off the street. A simple look in and you'll want to stop for a moment to check out what's inside. My favorite of these stores (Kramerbooks... where The Husband and I even took some engagement pictures) even has a cafe known for it's pie. You can peek the pie counter from outside. It's nearly impossible for me to walk buy without wanting to pop in for a book and a slice of goober pie deliciousness. (I've even taken to walking on the other side of the street to decrease my temptation.)
Window shopping often has to suffice for the only shopping I do that day... but it makes me happy. I know that, in the future, I will be one of the customers on the inside, perusing the shelves, and finding my next read.