The current system is to add an answer to What questions should be considered to close by 500+ users? for question to be closed, but it is not obvious what to do when the question are closed. The closed questions are then mixed with questions to be closed, which is impractical. Should we delete the closed questions ? Add another "community wiki" answer recording all closed questions ? Use another system ?
Or maybe another possibility might be to forget about this ad-hoc system altogether, as there are now about 25 500+ users and many others are close to 500. I suppose this is enough to make the voting system work on its own.
So I'd suggest to start a new CW meta-question that would only be for users that don't yet have 500 rep. Because if you have 500 rep already you don't have to post about bad questions; just go ahead and vote to close directly.
Although right now I thought about another related matter: cleanup of old questions. Probably another CW meta-question should be started for this. The rationale here being of getting attention of all the community to close old questions that went unnoticed and are unlikely to be spotted by enough people to close them anymore.