Mcdonalds - crappy product and service one day put me over the edge. They were never a good company to support to begin with. Funny thing is I volunteer for Ronald Mcdonald charities though
Burger King - same as above, too many burgers that were nothing like the photo, nothing.
Telus - I could almost get over the horrible commercials. But I had internet with them for 3 months and it was the worst possible internet service I ever purchased.
Apple - for reasons previously mentioned in the thread.
TV/Movies with scientologists as the leads (including Simpsons, Will Smith movies) Or other actors I don't want to support like Charlie Sheen. NBC might be soon.
Live pet stores as previously mentioned. Though right now I don't have a pet, when I do get a dog it will be from a real breeder (or shelter) and no live pet stores for supplies.