In this forum, they share clicks- http://www.jlvelasco.com/forum/ that helps to find webmasters with same interests to share clicks. The intersting thing is that you can share clicks only if the ads of other websites interest you. Whether it affects the adsense policy?
If people put as much effort into getting legitimate traffic as they do into getting around the rules... As I read the TOS, you may not do anything to encourage clicks on your ads. You can't pay people, even with clicks, you can't put posts in non-adsense blogs saying 'please click', all you can do is get traffic and hope that generates clicks.