[tor-dev] Request for references for anonymous blocklisting (blacklisting)

I'm putting together a proposal for adding anonymous blocklisting into the Tor such that websites that block Tor can block single problematic users instead of all Tor exit nodes. Towards this end, I am looking for papers/prior work in this area to draw from. Pointers anyone? Enjoyed the Iceland conference. Thank you Roger for inviting me! I aim to be contributing to Tor more over the year. -Virgil