I'm guessing this wouldn't work now (or does anyone think it would?), but it might have worked in early days when Google and others hadn't worked on identifying suspicious clicks.
I'm also interested if there is any law that would cover this?
This is different from someone who has an agreement with Google trying to defraud Google -- which would clearly be illegal.
However, it might be seen as a denial of service attack (though the intention is not to deny service - it is to just cost them a lot of money).
Note: i'm a former academic with an interest in social movements =)