I would guess that every multi-national company has someone, somewhere promoting a boycott of their products. There is an individual on a forum that I frequent advocating the boycott of Google. Not because of their dealings with the totalitarian State of China, but rather in response to the punitive nature of their page ranking system on bloggers.
I have an aunt who is an environmentalist from way back before it was cool. When I was visiting her in Toronto as a child in the mid 80s, she was boycotting EXXON. Boycotting huge companies that have a wide range of products can be a personal hardship. My aunt would drive past Exxon stations when she was close to empty and look around for an alternative. In the small community where I grew up, there is no alternative to Exxon.
Kraft is a great case study for boycotts. This is a huge company with almost countless different brand names. There have been boycotts against them for a wide variety of reasons, from their advertising of cigarettes aimed at children to their sponsorship of the Gay Games. If you are a consumer of processed foods, boycotting Kraft is very complicated. Oh, I should say that I think the AFA call for a Kraft Boycott in response to their sponsorship of the Gay Games is deplorable and ridiculous. A search on this subject reveals that criticism of the boycott and support of the Gay Games totally swamped the call for a boycott. Maybe the AFA should call for a boycott of Google for placing GoodAsYou.org higher in the search than the AGAPE Press. Why does the Christian website name sound gayer than the gay one?
One boycott that I support in principle, but probably fall well short of in practice is against the humongous food company Nestlé. The main thrust of this started in 1977 and the company has abandoned SOME egregious policies and practices in SOME regions and spent much money on defensive rebranding in various sectors of its enterprise in the interim. This is a very big issue and I encourage everyone to read about Nestlé.
The problem with boycotts is that the mass market is not as responsive to complicated messages as it is to simplistic advertising. Lobbying governments to impose restrictions on advertising can have a much larger effect. I read that Brazil has an outright ban on advertising of baby formula. One major issue that people have had with Nestlé is its aggressive marketing of formula to poor people who would be much better off breastfeeding. Brazil and other countries have also imposed labeling restrictions on baby formula.