By special request from my friend E.L., who is awesome.
There is an absolutely enormous quantity of stuff that I could write about apples. Baking with apples narrows it down somewhat, but not terribly much. So I'll just take a slice of that topic and offer the best of baking with apples that I have rolling around in my brain.
Apples are a great subject for baked goods. They're tasty, they're cheap, and they can be used in a lot of ways. The only real problem I have with apples is the chore of coring, peeling, and slicing them. This is extra difficult when your hands and wrists are in a lot of pain from arthritis, fibromyalgia, and/or carpal tunnel problems. My difficulties were eliminated with one great little piece of equipment, however:
This is an apple peeler. You stick it to a smooth, clean surface, impale an apple, and turn the crank. It peels, cores, and slices the apple all at once. You're left with a spiral-cut peeled apple. I usually then quarter the apple and use a paring knife to trim away any missed core bits (they're unpleasant to bite into, especially in baked goods). You can also choose to leave the peel on while doing the slicing/coring, or peel the whole apple and leave it whole and uncored. The resulting sliced apple pieces are absolutely perfect for baking, and it takes very little time to get through a lot of apples.
Once you've got your apple slices, you're going to want to do something with them, right? Whether it be pie, crisp, or bread, there is a basic recipe that I use to get the apples ready for use. For every 5 medium apples, I use 1/2 cup flour, 1 tablespoon cinnamon, 2 tablespoons lemon juice, 1/4 teaspoon nutmeg, 1/4 teaspoon allspice, and 1/4 teaspoon cardamom, about 1/2 cup brown sugar*, and the tiniest dash of cloves. If you really want to get spicy, add in some ginger, fresh or ground (don't go overboard--a teaspoon is usually enough). I then use my freshly scrubbed hands to mix the mess together. Using a utensil to mix is just inefficient and annoying, and if you don't like the stuff in your hands, you can toss on some disposable gloves.
After mixing it up, I taste a slice to see if it needs a bit more of this or that. Some apples are less tart, sweet, or flavorful than others, so you can adjust the ingredients to get the flavor you like. If your apples are particularly juicy, add in extra flour to absorb the moisture so you don't have a liquidy mess. Before throwing on the top crust, be it for crisp or pie, dot the apple mix with pats of butter.
Apple selection is relatively important. There is a lot of information online about which varieties are best suited to different purposes, so I won't go into it here. I'll just briefly say that, while it's easier to start with a good baking variety, you don't always get to choose. A lot of my baked apple stuff is for the purpose of using up the last of a bag of apples, and apples that are good for raw eating aren't always ideal for baking. So, be aware of the texture, sweetness, juiciness, and tartness of the apples you are baking, and add extra flour, sugar, or lemon juice to make up for it.
Partnering apples with other fruits is a good way to bring out flavor. Cranberries are my personal favorite apple partner. You can use dried ones, which are fairly inexpensive, or pick up fresh cranberries in season. An awesome thing about fresh cranberries is that they keep for a pretty long time in the freezer, so you can stock up a bit when you find them available. You can also use raisins, especially for very tart apple varieties; they add sweetness and texture. Just be aware that not everyone loves raisins, and they tend to look like little bugs in the pie. Cranberries are much prettier.
The best thing you can do is, start with these basic tips and just run with them. Be creative. Don't be afraid to try new things. If you're in doubt about an idea you have, make a tiny version of a pie or crisp in a small tart tin, using only one apple. Enjoy :)