Avengers Fanfic/Fanworks Search Community

Hey y'all! Okay, so I know I am going to spectacularly fail at this; I am new to this community and this is my first post, so please be nice to me!! :)

Okay, well I hope you guys can help me: I'm looking for fics which are mostly Tony-centric, with him being majorly underestimated... Like, he is secretly kick-ass, but people don't know/realize because they can't get past arragant exteria...
I would also like Tony with powers, or awesome abilities of some sort... maybe Extremis!Tony, Mutant!Tony, Assassin!Tony, Hacker!Tony, Doctor!Tony... Basically anything like that!! I have to say I do like angst, but I don't mind either way.
I know this all sounds super vague, but it would be awesome if any of you guys could help me out!

I don't mind gen or het but I do lean more towards slash... ;)

Thank you!!

Okay, late edit but I literally just figured out how to!! Many MANY thanks for all the incredibly awesome responses, I am still feeling slightly overwhelmed by the sheer awesomeness of it all, you guys rock!!
More fic recs are still forever welcomed, and I'm changing my search criteria to be a little more specific, to non-human!Tony or at least complete BAMF!Tony!! ;) Many thanks all you awesome people; much love!