Paid to click websites paid the users to click an ad that you the advertiser paid to show..this is obviously extremely effective in raising alexa rank, but from my experience, leads to no sales unless you are promoting a paid site and want to get referrals. Anyways, do you thing $19 is too much to pay for 1000 30 second long visits?
The problem is, most PTC sites are subject to abuse by the use of AutoClickers. If you want natural targetted hits, just do some SEO work.
I agree, I only found one website which had 30 invisible links and a visible one. This is the only one I would even consider.