Well, besides the Harry Potter books coming out, from five through seven (as I was reading the books but not fandom when four came out),

Oh, yes, HP was a big deal. I missed the boat on five, but I was there for six and seven.

or the Stephanie Plum books back when I was in that minor fandom,

OMG! I inadvertently caused wank on a Plum-related message board in the dark ages by suggesting that Ranger was gay.

the only big fannish moment I've been around for has been the final episode of Star Trek: Voyager.

That does not sound like happytimes, from your description. Ouch ouch ouch. *shakes fist at canon writers everywhere*