I think it would be useful to have a listing of ESRI Add-Ins that included links to descriptions and software they are for (ArcMap / Pro / Catalog).
This information often seems scattered about based on the solutions they are currently supporting which is fine, but there may be a number of other uses for them - and they may not be discovered by users not seeking out those solutions. For example the Attribute Assistant has a million and one uses, but for a long time it was hard to find if you didn't know where to look (now it has it's own page).
I suggest having a landing page or listing of all the current Add-Ins in a format similar to the solutions documentation pages (example).
Maybe this exists and I simply haven't seen it yet...