It seems like I used to have a list a mile long of things I didn't buy or places I refused to shop at. But most of them seem to, at least, not be relevant any more.

Wal-Mart comes to mind, but it's not really hard for me to avoid, and, regardless of my politics, I'd probably avoid it anyway because of the fact that it's such a terrible store.

Carmike Theaters, but that's also mostly because they're terrible, although there's some element of politics, too, though it's more "treating employees badly" than anything else, though they do have a strong (and absurd) anti-union stance.

Exxon, for environmental politics. I know, they're probably not any worse than any other oil company, but they demonstrably showed themselves to be indifferent to environmental concerns, and, these days, it's almost more the fact that they didn't simply clean up after their own mess. The lack of personal (where, in this case, "personal" means "corporate", not that I'm promoting corporate personhood) responsibility really pisses me off lately. I kind of prefer Shell, as they tend to be less politically conservative in their donations than others, but they're somewhat infrequent around here.

On the flip side, I try to frequent locally-owned stores in favor of big chains, from record stores to pharmacists. This has a little to do with politics, but at least as much to do with the fact that while the big chain might have a better selection of stuff (though even that's not usually the case) the locally-owned stores treat me better. That part shows through even in choosing one big chain over another, though.