Final Solution
thunderdome.surlyhorns.com
Executive Summary
No poster (aside from spammers) may ever be banned by a mod again. Instead posters are immediately restricted from posting, and are sent to Thunderdome.
In Thunderdome, The Banished can post whatever they want. It's a trash board. The catch is that, in order to have their posting status on the main board reinstated, they must hit a rep threshold from posts inside Thunderdome.
Rules
Only The Banished may post in Thunderdome.
The Banished may not rep inside Thunderdome.
All registered posters may read Thunderdome.
All registered posters may rep inside Thunderdome.
When one of The Banished receives enough positive rep in Thunderdome, his or her posting privileges on the main board are reinstated.
Each time a user is banished to Thunderdome, his or her rep threshold for reinstatement is set higher. Fibonacci. This time, it's +10 rep. Next time it's +12.
Additional Recommendations
Thunderdome must never be referred to as "the Thunderdome." That's stupid, and makes you look like an ass.
Likewise, The Banished is a proper noun and should always be capitalised. Branding.
Thunderdome does not have topic-based forums, only one big stupid piece of shit.
All users who are reinstated from Thunderdome have their rep completely reset to zero on the main board.