(A tip o' the hat to DaveH from Kim Du Toit's comments for the pointer.)
I keep what I call the Levi's List. It's an informal list of companies or groups I try not to do business with because I feel they are working against the things I'm working for. It's named the Levi's List in honor of the first company to land on it, Levi Strauss & Co. They got on it by actively supporting groups who work against our Second Amendment rights.
It's been pretty short until now. Yahoo Business has this piece about business leaders who are supporting the Kerry/Edwards ticket. It's now a good bit longer.
Among the companies who's gear I own, but will not buy more of are:
Columbia Sportswear (ouch, I really like their stuff)
Leatherman Tool Group
I really hate this, but I refuse to undercut my own efforts by buying their products. They're welcome to their opinions (I value the First as much as the Second), but my money spends anywhere--and it their case it will spend elsewhere.
For your convenience, I've made each name above a link to a customer service "Contact Us" page. Feel free to contact them and let them know what you think of their decision.