I make chicken soup with leftover chicken, chicken broth (about 8 cups, I use chicken base in a jar with water, but canned broth is good too) , a bag of frozen mixed veggies, and a 1/2 lb of dry pasta-I prefer rotini or mini bowties. I add a generous TBSP of jarred pesto (LOVE the pesto from Trader Joe's, I use a lot of it!) and serve. The whole soup can be done in like 15 min and seems to improve with reheating the next day.
my other favorite with leftover chicken is a fruity chicken salad. 3 cups of diced chicken, 1 small can of pineapple tidbits, drained, a small can or mandarin oranges, drained. about 20 grapes cut in half and 1/2 cup of chopped pecans. 1/2 cup of mayo and 1/4 tsp of curry powder. This is good just on top of lettuce or with whole grain bread.