There's Gaijin by Carrotglace
http://www.fanfiction.net/s/404359/1/
I really, really, really, hate SI's, but this works extremely well. It's often goddamned hilarious. It has Sailor Moon along with other things.
And an oldie, but goodie
Dire Fates a Hellblazer/AMG crossover
it's complete and badass, with a complete sequel as well.
http://www.fanfiction.net/s/273422/1/
You don't need to know much from either series
It's top notch.
For really good antihero fiction there's
Heroes Die and Blade of Tyshalle
by Matthew Woodring Stover
These are spectacular fun with grit and balls. Big gritty balls hahahaha
These are must own...no question.
In Manga, Blade of the Immortal is pretty decent, and I agree with Alathon that Moorcock's Elric series is great.
Have fun reading.