You could definitely replicate Ms.Scribe's tactics (which aren't that clever, in my view -- she lucked out with timing, in that she appeared just when LJ started to become the new fandom area); I don't think anyone could repeat her results, though. HP fandom was huge, between the books and the movies, and there's nothing that's so omnipresent and/or a cultural touchstone -- no fandom is going to make a big deal out of a meetup for a movie premiere, not now.

Every fandom has a certain shelf-life and period of peak activity, but HP was odd in having two major forms of media being released simultaneously (the books and the movies), so that 2001-2005 (post-GoF, pre-HBP) era was just... huge.

I was a BNF in a fandom. It's not hyper-interesting, but it's easy to achieve if you enter at the right time. Honestly, timing is probably more important than content, as God knows I wish I could forget my early fanworks. But I was consistent in terms of putting stuff out for fans, I networked with the "right" people, etc. If I'd known I could have gotten a laptop out of the deal, I wouldn't have spent so much time answering every e-mail with a sincere "thanks & [personal comment]" -- c'est la vie. This was before LJ, though, which changed the game significantly. Whereas in the pre-LJ days, you could possibly show up on a BNF's radar by leaving them comments in a guestbook or the like, linking to them, etc., and hoping they might check you out, LJ made it very obvious just how popular you were. Sockpuppeting makes more sense there, since having a sizable "friends of" list will increase the odds of other people friending you, because they'll assume you're popular. (Same thing happens on Twitter.)

This is why I just lurk, man. It's so much less effort.