I'll play...
My go to moves lately are mixing in chopped bacon, ground sausage, and/or cheese into the ground beef. I picked this up from my butcher shop that makes infallible bacon, cheddar burger patties (at $2 a burger). The extra fat and oil from the meat and/or cheese make the burger incredibly juicy. Even well done patties remain somewhat juicy. Closest thing to an official recipe would be as follows:
5 lbs ground beef (roughly 85/15 mix)
1 lb bacon (rind off)
1 lb shredded cheddar cheese (usually mild, but depends what I have available)
Combine in large mixing bowl with freshly washed hands. Once mixed, form into 6oz patties and you’re good to go. I prefer to indirect heat my burgers and flip often to minimize the juice from dripping out (seems to work very well). Also, sometimes I'll throw a chunk or two of pecan wood into the kettle for some added smoke flavor. Salt and pepper to taste right before the grill. Hit em with more or another cheese towards the end. Dress how you see fit (lettuce, tomato, onions, etc.)
I’ve recently been experimenting, with great success, adding chopped mango into jalapeno chorizo. I’m thinking I may turn this into a burger of some sort.
EDIT: Edit going in while there is only 3 replies to this thread. Not everyone will agree but do not smash the burger with a spatula at any point. Leave it alone, she's happy being chubby.