Kidding, kidding. Seriously, though, this bit right here:

Split visitors up according to source where they come from, returning visitors get different treatment as search and social media users

is not exploited NEARLY enough.

If you own a Wordpress blog, there is a plugin called What Would Seth Godin Do, which shows new visitors to your blog coming from search engines a discrete customizable prompt to sign up to your RSS feed.

You can expand on that general idea. Do you display advertisements? Do you display them to everyone equally? Do you have any reason to think that is optimal? Try splitting your users into two groups -- the community you've built (who are your core fans and spread your stuff) and transients (someone who just arrived off a Google search and, most probably, won't stick around). Nobody in the core fan group clicks on your ads, since they come there for you and not for AdWords -- so turn them off, and enjoy the increased visitor loyalty and spreadiness.

Many people in the Google search group are looking for something not on your page -- the AdWords ad (and Google) gives them a second bite at the search apple. Show them the ads.

This will result in vastly higher measured CTRs and higher quality traffic (no misclicks from core users who were aiming for something else), which will make your advertisers happy and might well be revenue maximizing, while making your regular users love you even more.

P.S. Did I hear someone say you could split test this?