Brainstorming Trust System Ideas

I'm sure this thread exists somewhere already but in my searching I couldn't find it. My hope is that we can brainstorm some good ideas in addition to what deimos has already proposed.

The recent discussion about lobste.rs reminded me of the fact that they use an invite system to limit the effectiveness of spammers and manage an invite tree to see the relationship of user accounts. A modified invite tree system would go a long way to help the trust system be more effective while not being stifling.

While it (unmodified strict invite system) would definitely make it more difficult for people to join the site the benefits of such a system cannot be overlook. Even a naive system where we would limit new accounts to require current users to "vouch" for new ones would have noticable benefits later on down the line. The main benefit of this is that users who are a source of consistently inviting troublesome accounts could be held responsible. The added benefit is that you would be a little more conscientious of the people you invite as it would affect your reputation as well.

The naive approach to this system would be a strict invite tree-based site. The only way you could get an new account on tildes is to get an invite from a current user of tildes. Like lobste.rs this woud be a very good deterrent but also (possibly unnecessarily) stifle growth. Such a system is a good starting point but I believe since a lot of effort will be put into making the trust system effective, we can do better if we put in some creative brainpower and work.

Possible ideas/tweaks for an invite tree-based system :
Parent account = person who invited user
Child account = person who was invited

• Users could create new accounts without an invite but would be severly limited in the rate they could post content (1 post a day), make comments (5 comments a day), etc. At any point they could be "vouched" for by a parent account with reputation (become child account) and those limitations would be lifted as though they had an invite from the beginning.
• User reputation would be impacted by child accounts (invite more, more likely to be punished as a result of children's bad behavior) to discourage individuals from becoming invite mills without repercussions.
• If a parent account is banned all child accounts would be demoted to "uninvited" status, child accounts would be encouraged to build up reputation to lose child status and become an independent (reputation-wise) parent account. Accounts would still be historically linked to parent accounts to pinpoint bad behavior down the line if it occurs.

Obviously a lot of effort has already been made by people a lot smarter than me to make such systems work and I think we can draw on that for tildes as well. I tried to look for some peer-reviewed papers and graduate level work about creating such a system but didn't come up with anything useful, perhaps you'll have better luck.