Ranma 1/2:
Ranma/Rouge matchup. Seems like it'd be interesting, and I've yet to see it done.
Ranma/Ukyo matchup done in an interesting fashion. I like Ukyo, but most of the matchups I've read with her and Ranma aren't really done well...they tend to be either heavy on the saccharine, or just rather meh, all in all, with no clear progression as to how they wound up together. Then again, that seems common, regardless of the pairing.
More nongeneric 'other' matchups. Typically, Ranma 1/2 fanfiction tends to go something like...Ranma winds up with whoever. Everyone else winds up as the most generic and blatantly obvious couples ever. For example, if Ranma gets with Akane, Ukyo winds up with Ryoga (or rarely Konatsu), Shampoo finally gets landed by Mousse, Nabiki winds up with Kuno, etc. Everything just falls into the same old tired pattern, regardless of how interesting Ranma's matchup might be. Same happens if Ranma leaves Nerima for awhile and manages to avoid the pursuit squads. Just because Ranma's the main character doesn't mean that all the other side romances have to be boring.
Ranma finding out that he's
not on the top of the food chain (just because he managed to be Saffron...which was mostly
luck...does not mean that he can beat everything out there, or that Saffron is even the toughest guy out there),
without Ranma automatically get propelled to the top of said food chain, or at least being given the potential to do so. Ie, demons are shown, Ranma becomes a demon. Gods are shown, Ranma becomes a god. Cyborgs are shown, Ranma becomes a cyborg. Mythical beasties pop up, hey, suddenly Ranma's got a secret heritage or gets some weird side effect from beating Saffron or his female side was actually a drowned magical creature or something. Saiyans show up, suddenly Ranma's somehow a Saiyan. Youma show up, Ranma becomes a Sailor Scout...and so on and so forth. Not that I necessarily want him to be sidelined, but having him
always be the guy that kick absolutely everyone's ass?
Some sort of scenario where Ranma and several of the Nerima Wrecking Crew wind up carving out their own little kingdoms somewhere...either after some sort of mass destabilization worldwide, or them all winding up on some other world.
Naruto:
Naruto and Sasuke, both immortal, Naruto thanks to Kyuubi, Sasuke thanks to the Eternal Sharingan and/or some other plot device, having fun as time moves on towards the modern day.
Sarutobi
not being portrayed as some sort of easily hoodwinked senile old coot. Damn it.
Danzo
not being some sort of ultimate evil. Seems more like a ninja than most of the Naruto ninja, dammit...and his goals don't seem all
that bad. Yet in fanfiction, suddenly he's the madly cackling megalomaniac that's burning Konoha down to the ground? Bwa?
Older people
occasionally knowing more than younger people...what with the whole bizarre, "YOUNG PEOPLE ALWAYS KNOW BEST!" thing we seem to have going on.
Maijin Tantei Nougami Neuro:
...just...anything, really. I like Neuro, dammit. It'd be cool to see some whacked out crossovers involving Neuro...say, with Evangelion, perhaps, or even Haruhi...but I'd settle for just some good fanfiction in this fandom.
Evangelion:
An Evangelion/Shin Megami Tensai: Nocturne crossover. Because it seems like the two series ought to be able to fit together somehow.
An Evangelion/Persona 3 crossover. Not sure how it would work, but Gendo and Ikutsuki, not to mention Rei and Aigis...the idea nags at me. Especially possible connections between Shadows and Angels...Nyx and Third Impact? Eh. I'd like to see something done with it.
Planescape: Torment:
Fall-From-Grace promised she'd find the Nameless One eventually...one day. I'd like to see her try and do that, possibly with some of the other members of the party. Because Planescape: Torment was awesome.