I would like the same system to be used to prevent child pornography or stolen credit card details. Anyone can flag an item for removal, but then a panel of 5 random people vote whether or not to remove it.
I like your ideas, but this is a tricky one. To judge whether a flagged item should be removed, the panel members would have to view the item in question. In case of child pornography or other illegal items, just viewing them in order to judge might be illegal in itself.
I know I wouldn't want child pornography images in my cache and browser history and whatnot, even if it is for a good cause...