Well, it seems three of my applications have been inactivated. I checked through the four rule sets and I don't think I'm violating any of them, at least not deliberately. I am doing a fair amount of testing, so I do get rate limited from time to time, especially when testing the rate limiting response mechanisms. ;-)
The only other thing I can think of is that I've got four applications, and I really could combine three of them into one. I need at least two, because most of them are read-only and I don't wan't to authorize writes for those. Curiously enough, it's the three read-only ones that got inactivated.