Thanks for this helpful bag of tricks.
One request - if anyone's interested. I'd like a MOD to delete any unvalidated user after some period of time - say, one day. All the spambots I've seen give fake email addresses and never validate - they just want to be in the member list. If they were cleaned up automatically, at least it wouldn't be so much of a problem.
I also have a bunch of users who registered a couple of times before they figured it out. This would clean them up. (That's only an occasional problem, though, and can be done by hand with the phbBB admin toolkit
One implementation issue is that this would be sort of a scheduled task, so when to run it? I don't know if it should be done as often as every session start. Maybe on every registration? That will be often enough unless the bots stop being a problem, in which case it won't be needed.