Actually, I don't know exactly how great or not this bit is, but I thought of the concept one day and googled it to see if it existed. It took a lot of digging, but I found it. (By the way, don't google this in images, for your own sake. Apparently they're not just for horses.)
It's a leather bit with regular metal cheekpieces, sold by a site based in Norway.
First, go here: Tools - Google Translate
Scroll all the way down until you see the different languages in blue boxes. Pick the one you speak (for me, English) and drag it to your bookmarks bar (not the drop-down list) on your browser.
Next, go to freehorse.no. Click on the language you just put on your browser (unless you're fluent Norwegian) and it'll translate most everything.
Click on the left-hand menu where it says Bit. You'll see them. It also give a good description of each.
(Sorry these are semi-ginormous)
The Original and the Pelham.
Horse wearing the Original. I would probably prefer it to just act like a regular snaffle, being able to attach to a bridle and such.
A well-worn Original bit.
I'm thinking this could be a good medium between bits and bitless, and could be a good trail or 'home' bit. Maybe a starting bit? Of course, it's not going to be as refined as a dressage bit, but what the heck.
I wonder how hard these would be to make?
The price is a bit (okay, a lot) steep, though... $104 American dollars for the Meroth Original Laerbitt and $232 for the Meroth Pelham Laerbitt, but with reins. Not including shipping and customs into your country.
What about metal bits wrapped in a thin layer of leather? I imagine leather would also help with the nutcracker effect of single-jointed snaffles, too. We use leather everywhere else on our horses, why not our bits?!