This is an oldish thread I know, but I thought I would share. I make shredded chicken for mexican food in mass quantities (there is a high demand for tacos in the apt.), and then put them in little freezer bags for personal use later.
Just put chicken breasts in a pot, and throw some onions and garlic in there. I usually cut up about half an onion for two breasts. Fill with water until the chicken is covered and boil it until it's cooked all the way through (should be 165 F on the inside, but if you don't have a thermometer, it takes about 35 min.) Save the broth.
Let it cool enough to handle and shred it with a fork. Then put it in a pan with cumin, black pepper, diced tomatoes, and whatever you want basically (black beans, chopped onions, olives, jalepenos, whatever you have). Cook it for like 20 seconds, then add enough of the broth to moisten it up and cook it for another few minutes.
And that's it! I like to eat it on corn tortillas but it's also good with just lettuce. And you can just freeze it and heat it up whenever you want. I strain and freeze the leftover broth too, for other recipes.