Idea for this add-on:
If someone has read a post and would like others to become aware of it - without others knowing about it. This leaves only a few time-consuming options, e.g. starting a PN.
With this add-on it is easy: type in the username and send. The user(s) receive an alert.
It serves to provide simple and quick information to others.
Personal note: I am not yet happy with the name of the add-on, I can't think of anything more concise or better.