The main one is Walmart, but if I'm being really honest, although it started out as a boycott of their corporate practices back when I was a wide-eyed college student, at this point it has at least as much to do with the fact that I'm a snob and I just don't like that place.
I think that Gamestop fucking sucks and they do things that piss me off, but again I think the snobbery has more to do with why I won't go in there.
Other places mentioned in the thread that I have never visited include Jimmy John's and Chick-fil-A, but in both cases it's just something that I've never gotten around to doing, and not some kind of boycott. Jimmy John's just doesn't look like something that I want to eat, and in the two small towns where I spend 99.9% of my time, we don't have a Chick-fil-A. John Schnatter is a huge piece of shit regardless of what happened with the whole n-word thing, but more importantly their pizza is complete garbage.