As far as I know, Google hasn't bought out Yahoo yet (interesting how Bill Gates gets in trouble for "monopolies" when huge corporations like Google can buy up stuff like Dejanews and Blogger and nobody says a word...)
Anyway, don't use Google as your home page or your search engine! Use Good Search.
It's Yahoo's search engine, and by using it, and choosing a charity of your choice to receive the money, you will be helping out a charity. It's only a nickel or so per search, which is not much at all, but hey, every lil bit helps out.
Is the URL for Good search.
If you don't have a charity already in mind, may I suggest either:
Alzheimers CURE Foundation (one of several Alzheimer's charities participating in this program)
International Women's Air and Space Musuem