Then A&E did its miniseries with Jennifer Ehle and Colin Firth, and there was a huge resurgence in the fandom, and here we stand today. I actually started reading this stuff because my friend sent me a link to an absolutely bizarre P&P/X-Files crossover (I kid you not), and I was floored that such a fandom even existed.
So, here are some guidelines.
1. Be very happy with your decision to explore this fandom. As a rule, the writing you will see here is far superior in quality to other fandoms. Not that there aren't fabulous gems in every 'verse, it's just that you usually have to wade through literal mountains of crap to get to it. Among Austen fans, though, I'd say that you only have to wade through moderate hills of crap, and there you stand at the shore of a fairly expansive sea of well written fic.
2. This is a small fandom -- there are only a few websites out there, but they're very good ones. The two that I frequent happen to be huge.
3. 99.9% of these stories are absolutely schmoopy romances. They aren't necessarily sugar-sweet, though, and certainly, you won't find many of those sorts on this site (I like keeping my blood sugar low, thank you). But it's important to keep in mind that the plots of these stories are pretty much going to be uniform -- you've read P&P, right?
4. Due to the success of the miniseries, a few scenes that actually aren't in the book have made it into fanon. The one that comes immediately to mind is WetShirt!Darcy -- he pops up in most of the fanfic I've read, at any rate. There are also a few lines of dialogue that are oft' mentioned, but aren't in the actual Austen if you look.
5. While (duh) these stories are all Darcy/Lizzy, I've seen a fair amount of variety in the other pairings (inasmuch as it's possible). A bit of Fitzwilliam/Jane, Fitzwilliam/Charlotte, Fitzwilliam/Georgiana, and Fitzwilliam/Anne surfaces every now and again -- our Colonel does get around, doesn't he? Oh, and a bit of Collins/Mary, as well -- I've always wanted to write that pairing as an epic love story; they don't get nearly the romance they deserve...
Enough of that -- go, read!
Hayseed