Another idea is using some cooked rice (best already cold), and making nasi goreng. Basically, fry a chopped onion, add chopped garlic, add handfuls of veg (a mix of whatever you have - tinned sweetcorn, peppers, mushrooms, finely sliced carrots, peas (fresh or frozen), French beans, sliced courgette, etc all great), add a mix of (tuna (tinned), prawns (from freezer usually) and cooked chicken), throw over a couple of tablespoons of mild curry powder, add cooked rice, toss it all about for a few more minutes, serve.
It's great for using up little bits of leftovers and last few veg, and/or a meal from freezer/storecupboard.
Otherwise, for leftovers other than the pie:
Chicken and mushrooms with a cream and white wine sauce, perhaps some tarragon, served with pasta/rice or mash.
Stir fry (Asian type) again with a mix of veggies (sliced Brussels sprouts, peas, carrots, onion, brocolli etc would be nice) and some rice or noodles. Packet of sauce (hoi sin, chop suey, sweet'n'sour etc), or just some Chinese rice wine or sherry, with a good slug of soy sauce works well.
Pasta bake - also with lots of veggies and a tomato or a creamy or cheese sauce. Actually, pasta bake is the second iteration of that dish, as the first is the pasta with sauce fresh, and the bake is the reheated version (I tend to freeze leftovers for baking on a work night).
For the sambos: try DD's favourite - mix mayonnaise with some curry powder and chunks of chicken. She doesn't even bother with bread for that anymore (but she will make it herself so I can get on with dinner).
Or do a toastie - slice of bread with pesto, sliced chick on top, perhaps a slice of tomato, topped with grated mozzarella or some nice strong cheese (mature cheddar, gouda is nice, or edam), and toast as an open sambo under grill.