Okay, I've got a suggestion which is somewhat "out of the box". I was thinking about purchasing patents to medications, that could then be used to treat those that can't afford them. First things that spring to mind are AIDS, Malaria or TBC medications, that are currently completely inaffordable for many people world wide. I'm pretty sure it wouldn't be easy to convince pharmaceutical companies to sell even one patent, but if they were explained that they 1) would get a positive publicity that's very hard to buy otherwise, 2) get money from the sell and 3) still can sell the generics, so they're not completely losing money, it might be possible. I know, it's technically not free knowledge in the way we are referring to it on the different wikiprojects, but I think this could nontheless be a worthy cause.
Thanks for listening,
Lennert B