> One thing I've been hoping for is inventing some form of advertising that was actually fun for the user -- fun enough that they would not want to block them.

You should take a look at the sponsored lenses on Snapchat. Nowhere else on the internet are ads so engaging and enjoyable. This is also why I think Snapchat had a chance to really take on Facebook, until FB sucked up and started copying everything from Snapchat.