Here is a great easy, healthy recipe I just made from Pillsbury Slow Cooker magazine, January 2010. I also found this recipe on Food.com.
Chicken Tortilla Soup
Spray 3 1/2 to 4 quart slow cooker with cooking spray. In cooker mix all soup ingredients except cilantro.
Cover and cook on low heat setting for 6 to 8 hours. (On a personal note, I prefer to cook on high first for at least 3-4 hours, then turn the heat down- I just like to know that the ingredients are first getting cooked on high heat)
Stir in Cilantro and increase heat setting to high. Cook 15 minutes longer.
Serve with the garnishes, or add your own twist to this with your favorite items.