[I had this queued up to go in February and never published it... but I am desperate for fodder. Not sure where I was going with this, though.]
The Thumbs Forward Grip. Prolly been around a while, but I first learned about when all those bloggers went to the Todd Jarrett Camp at Blackwater!.
This changes everything for a right hander using 2 hands. Where, with one hand firing, reaching the buttons you need to reach on a 1911 is difficult for some, putting the support hand up there in a thumbs forward grip and all the fiddly bits become accessible if you want. If you are the type that releases the slide via the slide release lever, it's there is where your thumb is, and you can reach that mag release easily too ifn you wanna.
Of course, for lefties, these bits (mag and slide release) have always been available to our longer finger, even shooting one handed. A righty needs the correct length thumb, and not all shooters are issued this. A lefty's only real disadvantage is with a 1911 with a non ambidextrous thumb safety. And you can work the safety one handed with practice, anyway.
I've thought about getting a left handed 1911. Port shooting the empties off to the left, mag release and slide release on the other side... But I've trained out the issues a lefty has, and like the advantages I get, anyway. I don't wanna muck things up relearning stuff.
The same goes for a lefty revolver. Or anything but a Smith operating system on my revolver (sorry Colt).
No, the only real advantage I could get from any lefty specific gun is a lefty bolt action rifle.