I think the mistake people make is to think that there are specific things to cook in the airfryer. Rather, as @badwolf82 says, just think of it as a very small, very efficient oven. So in the same way that sometimes you use the microwave because it's a quicker and more convenient way to heat something than on the stove, the airfryer is a quicker and more convenient way to cook things you'd normally put in the oven. Over the last week, here is what I have done in my airfryer:
Par-baked baguettes for the DC's holiday camp packed lunches (180 for 5 minutes, then I usually leave them standing as I'm running around. I'd do 6 minutes if I was actually going to take them out instantly!)
deboned chicken thighs I'd stuffed with garlic, herbs and cream cheese and then wrapped in parma ham. They took about 15 minutes for 5 largish ones (I have the single draw ninja).
Crumbed chicken "steak" aka "posh nuggets" with fries for DD.
An pre-prepared and frozen (but not previously cooked) individual sized spanakopita for a post-camp snack for DS.
Salmon fillets (I can just squeeze 4 into my airfryer).
Frozen croissants (the unbaked ones) and also to refresh waffles made that morning.
Other things I do regularly:
Any kind of pre-made fish cake/nugget/fish finger etc.
Tomatoes and onions roasted
Quick roast potatoes when in a hurry and just cooking for one/two people
Baked feta
Sausages