One thing I realized from my .1 free bitcoin promotion of mokimarket.com is that this marketing strategy has great potential to help sites get users to test it out.
If your willing to pay google $1 just to get someone to look at your site; why not cut out the middleman and pay .1 or .2 bitcoins to get user to not just look at your site, but also register and test out your site.
Might be cool to add a new forum in bitcointalk that is solely for getting users to sign up for new website in exchange for microbitcoins payment. Users could easily earn several bitcoins every day just by signing up and registering for new bitcoin friendly sites.
What do you guys think?