Solve media are captcha's that fight 'banner blindness', as the phrase you make people type could be your selling point. And you all remember what people told you when you were a kid; if you want to remember something write it down. So here you can have captchas making people type anything from "choose Jif" to "yadda yadda yadda" and "all the adnews not fit to print". Why not.
As a publishers there's advantages as well, for one thing the graphs on your end are clear and quickly updated, allowing you to see which site of yours is performing better (if you have several).