Here's a pic of the Piper Enforcer, a turboprop P-51 Mustang derivative:
That B-17 Dart conversion was wonderful to fly but didn't last very long before it smacked the ground fighting a fire. They used to zoom to altitude, shut down the two outboard turboprops and cruise home on the two inboard engines. I've read some astounding stories about the excess power that was available. It was built and flew out of Wenachee, WA.
The pic of the single engine B-17 with a turboprop in the nose is a photoshop spoof. But they DID put a big turboprop in the nose of one while retaining the four piston engines.
Here's a real rarity, a B-47 with turboprops on the two inboard engine pylons:
It apparently had astounding acceleration and would walk away from the pure jet B-47 until it reach top speed, at which time the all-jet B-47 would eventually catch up and pass it. Great climb, too.
Here's a turboprop Gloster Meteor called the "Trent Meteor:"
There are more around. The Italians put a turboprop in a Cessna Bird Dog. There was a turboprop Douglas Shyraider.
Here is a 3-turboprop DC-3: