An interesting idea, that's stuck around in my thoughts but escaped elaboration until the recent issue of an influx of new users became prominent, is the idea of pseudonymity.
Pseudonymity is important because although a real-name system works fine for stopping most low-effort or spam-like posts, not every potential participant on LW would want to use their real names.
However, there becomes the problem that the moderators can't review an arbitrary number of new accounts due to practical constraints.
And without this review process, there would be too much low-quality content (from what I understand) flooding the front page. Which would decrease the credibility of the account that wrote it, but also slightly that of other pseudonymous accounts by association since most readers will have lingering suspicions of the possibility of someone creating multiple accounts.
So a way to resolve multiple issues at once is to charge for new pseudonymous accounts.
It ensures moderator time spent reviewing will be compensated, greatly increases the bar for attempted spamming or trolling, and increases the credibility of new pseudonymous users.
As every reader will understand, if sufficient announcements are made beforehand, that whoever behind the account spent real money on establishing it, thus they would be unlikely to behave recklessly or create multiple pseudonym accounts unless they were highly motivated.
The exact details of implementation will likely have to be more closely examined before it could be practically added.
I'm unsure if this issue has been raised before on LW, but I found the logic compelling enough to write this post anyways to see if anyone has suggestions
Perhaps impersonation or name formatting will be a problem in the future if this site becomes even more popular, but they're not a present day concern.
Whereas many present day concerns could be addressed by some combination of the aforementioned or other proposals.