I'm most intrigued by idea 5, but then, I have an affinity for incentive-based models. "Want your posts to be ad free for others? Click here" The downside of that is that it makes the site less attractive to potential advertisers, as one can imaging that the most popular posts, from the most popular users, are the ones most likely to be ad free. In that case, attracting quality ads to makeup any shortfall could be difficult. Generally, however, I think that idea is brilliant, as it presents a clear carrot-and-stick for each user.
Yeah isn't #5 a bit like letting websites that can afford it load faster? Eventually no one uses the slow ones. Those of us who care most about the site will have ad-free pages, attracting more followers/views than the ad-heavy posts, in a sort of death spiral. I don't know how much hubski's server costs are, but I bet if they just opened a damn coinbase and said have at it, they'd get enough money to not think about this for three years. And who knows what new options will exist then.