"The hope is that the shared biases will be ones that the site owner considers valuable and useful..."
Then perhaps the name this site should be Overcoming (some) Bias. Or maybe Overcoming Bias (except mine). Or how about Overcoming (your) Bias?
I really hope you've thought this through. Every open social news site in history has rapidly devolved into a useless clusterf--k. You will get a semi-obsessed sub-culture of users with a few shared biases who effectively take over.
Setting aside the arbitrary volumes and dimensions, and ingnoring all the sprarkle and bling, the good Rev.'s Heaven consists of: "All inhabitants are honest and there are no locks, no courts, and no policemen."
Basically: agreement on what consititues life, liberty and property, then perfect respect for them. That may actually approximate Utopia, at least as far as Homo Sapiens is concerned.