Profilactor

Provides a choice of notification actions when users update their profiles. It solves a very well-defined and simple requirement of one of my clients, to keep track of profile changes. It is very narrow in scope.

It cycles through Profile details, optionally also user account details, and describes exactly which were changed. Quite a few configuration options are available.

It only requires the optional core Profile module.

It's the first proper (discreet) module I've developed from the beginning.

There are plenty of other modules that promise or seem to solve this (including Triggers/Actions and Rules and several more). I spent a lot of time trying them out. They either don't work or don't provide the configurations and robustness I want. They may be patchable, but how to do that is not obvious to me. In the end, this seems more robust and configurable for the client than plugging PHP into a Rules action, and then duplicating that code for user accounts and profiles.