I recently facilitated a workshop on using my lesson planning app, Spliced. Aside from learning how to use the app, many of the participants also learned something about the App Store: Apple really wants developers to make simple, concise apps. So when people say "there's an app for that," it isn't a coincidence. Apple actually wants it to be that way. In other words, developers like me can't make a "one stop shop" for all your teaching needs. Instead, we can release multiple apps, each with a pointed focus.
That being said, my app's "pointed focus" is organizing lesson planning materials and generating teaching documents from that data. Personally, when I need to do something else, I go and find another app. I've accumulated a few over the years and, prompted by the participants in my workshop, I've decided to share them here. They are split into two categories, "apps for planning and creating content" and "apps for teaching and assessing." Because I am a math teacher, some of these apps are topic specific, but I there are quite a few apps on this list that any teacher can use.