Here's a tip that my DH actually taught me (lol). He grew up with having his mom take whatever leftover meat (not hamburger) and put it thru the blender or food processor to grind it up. Then she used it as a lunch meat spread, I usually add mayo and mustard to it, and whatever seasonings you used on the meat adds good flavor to it.
My mom always did this with ham. She'd grind up leftover ham with green peppers (grinding them at the same time), add mayonnaise and sometimes a little sweet pickle relish and serve on rye bread - MMMM!