I love this community - you're doing great, and I've found such wonderful stories here!

Since you asked, I know I would find it helpful if you had pairing tags (and/or, in the titles, you could include a brief pairing - just a simple McShep or JB or Seth/Ryan or whatever name style you like, or even just slash or gen or het... that way, going through memories for each fandom, we could scan down for our favorite folks or genre...)

If you're expanding fandoms.. let's see... since you've got Stargate Atlantis, it might not be too much of a jump to go for SG-1, and there's lots of awesome stories there. I can't help being a Lord of the Rings fan, and my very first fandoms were Rurouni Kenshin and Inuyasha. There's an archive for Saitou/Sanosuke fics (Kenshin), with some really nice ones, like Rogue of Tokyo. I also absolutely adore Magnificent 7 (lots of talent there!), and I'm just starting to get into Supernatural.

One thing that I'd find really, really useful is if you could make a tag for fics that do a good job of introducing you to the characters. Often, that's AU's, but sometimes really good canon stories either provide you with relevant canon details or create their own backgrounds, so you don't need to have seen the show (especially if they're set early in a TV series, etc). I've pretty much never seen an episode of stargate (atlantis or SG-1), the sentinel, or mag 7 - but I got introduced to each fandom by following my favorite writers, and learning the characters through their eyes. So if you had a tag for "stories very good for someone new to the fandom" (however you want to word it), that don't assume any prior knowledge - dude, you'd make me a deliriously happy fangirl! Then, no matter what new fandoms you decide to start reccing, I'd gladly follow! :)

Oops - forgot to rec particular stories!

Here's an absolutely amazing Mag7 / Stargate SG-1 crossover (and there's a prequel and a sequel, both also by ZorroRojo)
http://m7slash.com/viewstory.php?sid=197

In the original Out West universe of Mag 7, there's a really amazing and long gen series, that focuses on the friendship of Vin and Ezra (and being the true slash fan I am, I sooooo read it as pre-slash).
http://www.nottasha.com/series.htm

Here's a link to my favorite Rurouni Kenshin fic - it's a vampire AU, really really well done, by Goldfish - scroll down to Rogue of Tokyo:
http://www.geocities.com/saitouinsidesano/authors-g.html

For Lord of the Rings, one of my favorite authors is Daw the Minstrel - she's a gen writer, and whenever I seriously, desperately need some warm fuzzies, I go to her. She's created her own world of Mirkwood, with a whole series of stories of young Legolas and his family (including some great ones focused on OC older brothers), with just the right mix of action and angst and fluff. Stories individually range from a few thousand to 50 or a 100 thousand words, and since they're all mostly a series, it's truly epic (and she lists stories in chronological order for the characters, right there on her author page): http://www.fanfiction.net/u/271521/

My two favorite slash fics for LOTR are actually pretty dark (which is rare for me, so you know they're incredibly talented writers, to hook me despite the darkness!). Cuil Eden is a much lighter BDSM sequel to the darker story Anestel - very, very hot if you can make it through Anestel to get to Cuil Eden: http://lotr.adultfanfiction.net/authors.php?no=1638

The other is Feud, by erobey - it, too, starts out very dark, but gets much better if you can stick with it: http://www.shadowess.com/slashfiction/viewstory.php?sid=326

As for Supernatural - one of my favorite Harry Potter writers is Gillian Middleton (she also has some great Sentinel stories, so maybe you know of her)... I started reading Supernatural because of her, and I recommend any of her stories. Hmm... Here's a link to The Promise (a great one, if you're not opposed to incest - tastefully and sweetly written - between the brothers) - and from there you can get to her author page on fanfiction
http://www.fanfiction.net/s/3197629/1/The_Promise

Oh my goodness, and because I'm an idiot and forgot to mention 2 fandoms (Harry Potter - I'm actually a Harry/Severus fan) and Anita Blake (that I mostly know only through crossovers) - here's an absolutely spectacular crossover for HP (it's Harry/Draco) and AB (there's a bit of threesome action with Nathaniel, I think). It's Black Magic By Moonlight, by beren_writes:
http://beren-writes.livejournal.com/93442.html

I have recently re-discovered Law & Order: SVU, which has a tremendous amount of potential as far as fan-fiction goes. My favorite, possibly OTP, pairing is Fin Tutuola/John Munch. Unfortunately, despite the potential of the show, most slash (and a lot of the het) stories have that 'I was written by a 13-year-old Barbie fan' flavor. But, despite the tons of chaff, an occasional grain of wheat can still be found. The two stories below are quite good - they deal with very adult themes, as well as past angst for the characters, but they also have happy endings. I definitely recommend them, but the author says that she will be taking them down soon, so get them while you can.
"Love is the Law" & "Black & White" by Melody, both found here (http://finmunch.fanfictiononthenet.com/melodyfm.html).

And if you like femslash, the SVU fandom is the place to be, since it has several very strong female leads.

From what I've gathered from her pages, she's had some trouble with flamers, and that's why she plans to take them down. Of course, I could be wrong.

Hey, I've just re-discovered an old fandom love of mine: The Big Valley! (don't laugh! those guys were hot!) Unfortunately this fandom is overrun with god-awful M-S like you wouldn't believe, as everyone wants to marry their favourite brother. Never have I seen so many grown-up women play house... Anyways thankfully here's an exception, one of the most beautiful romances I've ever read online:

http://www.angelfire.com/tv2/bvsmdm/Jemma.html

Enjoy!

Here's an overview: http://www.boxofficemojo.com/features/?id=2070&p=.htm

Heath was my very first TV crush when I was 13! :sniff:

Dang! Did I give my age away...? :grin:

Oh! I just found a huge Sentinel/Various Fandoms including SG1 crossover. The crossover aspects are mostly in the background, Jim and Blair are definitely the focus. Basically, this takes the premise/cliche 'Jim & Blair are kidnapped by the military' and runs with it. Surprisingly realistic, with slow and naturally developing slash element. Definite warnings for very explicit violence and emotional torture. But not in the way you might think. It is huge (1.3 MB in all) and very good. I really enjoyed it.
Nightmare Realized (http://saulsfic.kol.co.nz/slash/index.htm) by Saul.

I recently found your community and while going through past post I found this one; I don't know if you are still looking for new fandoms, but I thought I would give it a try.

One of my favorite authors, named Vathara (http://www.fanfiction.net/u/77482/), tends to write long well written crossover stories; her latest reaching 136,199 words and is a Star Wars/Rurouni Kenshin fusion (http://www.fanfiction.net/s/4031223/1/Shadows_in_Starlight). She does not write slash, but I thought you would enjoy a well-written story anyway. She has also written stories in Stargate: SG-1, Godzilla: The Series, Airwolf, Sentinel, Mutant X, Gargoyles, Yu-Gi-Oh, X-Men: Evolution, Rurouni Kenshin, Buffy X-overs, Danny Phantom, Final Fantasy VII, Star Wars and more.

Also, if you ever want more new fandoms and you don't mind a mixture of gen, het, and slash don't hesitate to ask.