Sorry for this almost-double-post (good to know, @Alamias), but in going through my DTRPG downloads I forgot one.
The big one.
The best one.
A Dirty World, by Greg Stolze.
People probably know him better because of Reign, Unknown Armies, Wild Talents/Godlike, Better Angels (mentioned previously).
A Dirty World is a game about living in the the 1940s and uses a system that I desperately want to make work elsewhere wherein you can do pretty much anything that doesn't take a lot of skill as long as your personality says you're confident in doing so.
If you want to deflect a scum mobster, you need to be confident in your righteousness. If you want to hit harder, you need to give up some innocence to throw your anger behind your punch.
These personality traits aren't just whatever number you want, but they come in pairs, and at a level they're mutually exclusive. You don't have "slight of hand", but if you're more sleazy than innocent your character is more likely to pick that lock no matter how much "skill" your character might have.
And the system is tiny. My explanation of why I like the system is about as deep as the system goes, and follows up with many specific examples because the idea of rolling "Persuasion + Purity" doesn't come naturally.
It is not a game of high worldly stakes. It's noir, through-and-through, and as part of a larger system I could take to it even faster than Apocalypse World for a new way of playing RPGs.