First off, if you are new to cast iron, do some googling on care and cleaning. It's easier than it sounds! Most new cast iron comes preseasoned, so you shouldn't have to do much to get started. Don't ever soak it in water or use the dishwasher. Use the bare minimum of soap and don't let it sit very long. I use a plastic pot scraper thing to get crud off and then do a quick scrub with the back of the sponge and rinse with warm water until the water runs clear. That's usually enough. Stuff comes off easier when its fresh or off a warm pan. I only reseason every few months unless the pans look banged up (my dutch oven tends to need it more often, but its ancient and prone to rusty spots).
Foods to avoid- rhubarb, lemon juice, spinach, turnip greens, collard greens, etc. I had a dumb moment the other night and since the cast iron was already preheated, threw some turnip greens in for a quick sauté. BLECH! The iron made them so bitter it was nasty and I had to throw them out.
Cast iron is especially nice because it can go from stovetop right into the oven or vice versa. I do a lot of steaks this way when I'm too lazy to use the grill - pan sear on the stove and right into an already hot oven. I have a dutch oven, a large skillet and small skillet that comes camping with me, and they are probably the three most used kitchen items I have, with the exception of the crock pot.
Skillet- CORNBREAD. CORNBREAD. CORNBREAD. Eggs, pancakes, grilled cheese stirfry, potatoes, Fried chicken/steak/fish, etc. Spinach and artichoke dip, or crab dip or cheese dip. Seafood - I do tilapia/haddock/seabass/scallops with a little black pepper and a slice of lemon or lime added at the end. The other day I did tilapia with an avocado/tomato salsa in a chipotle lime sauce, all in my skillet
Any recipe that calls for "searing" can be done really easily in the skillet as well. Just remember that when you remove it from the heat, it remains hot for quite a while.
Dutch oven - pot roast. soups, stews, and chili. I make a lot of turkey/barley/vegetable type soups. Sometimes I use chicken. Some times I use quinoa. Sometimes I use beans. I always use whatever random veggies are in my fridge. I never use frozen veggies and rarely use cans of anything, but that's my personal preference. I tend to lean towards whole/unprocessed foods for a good soup.
Some good recipes: Feel free to pick and choose ingredients to suit your tastes and your kitchen (IE, I leave out the yucky mushrooms. And I never have marjoram on hand and I usually add a bunch of other veggies)
http://allrecipes.com/recipe/hearty-barley-turkey-soup/
http://www.kalynskitchen.com/2006/02/second-helpingsturkey-barley-soup.html - this entire blog is awesomeness with lots of great recipes
http://southernfood.about.com/od/crockpotchili/r/r80215c.htm
http://www.thekitchn.com/dinner-recipe-french-onion-chi-144744
http://iowagirleats.com/2013/01/30/avocado-mozzarella-and-bruschetta-chicken/ - another awesome blog
http://www.skinnytaste.com/2011/10/crockpot-turkey-white-bean-pumpkin.html - yet another good blog
Seriously - pick your favorite meal, google recipes, and give it a try! Most crockpot recipes transfer really well to dutch ovens because of the long cooking times on relatively low heat. You can look for reviews to guide you, and eventually you get a sense of what works/what doesn't. Don't be afraid to edit and make changes if a recipe isn't exactly what you want. I hardly ever follow recipes and have cooked very very few inedible meals haha.
If you like Pinterest, send me a PM. I've got a ton of awesome recipes saved on there. And if you have a particular type of recipe you want to start with, I'll try and find you a good one
ETA: Remembered some other recipes I've recently done in the cast iron
http://www.bakeaholicmama.com/search/label/Quinoa - scroll down to the mac and cheese recipe
http://www.eatingbirdfood.com/2012/09/healthy-pizza-with-a-cauliflower-crust/
http://www.tasteofhome.com/Recipes/French-Dip - a crockpot recipe that was super in the cast iron dutch oven
