Thought I'd share a handy script I wrote up recently. You can find it at https://greasyfork.org/en/scripts/33347-profile-info. It adds a collapsible panel to profile pages that you can use to tag players with a difficulty (easy, medium, or impossible a la WarBaseExtended) and keep notes on players. A picture is worth a thousand words, so here are some illustrative screenshots.
Panel expanded, easy difficulty:
[image: puu.sh]
Panel collapsed, easy difficulty:
[image: puu.sh]
Medium difficulty button:
[image: puu.sh]
Impossible difficulty button:
[image: puu.sh]
Please feel free to contact me if you have any issues/questions/suggestions.
Edit: Added information to the panel title, as suggested by miros [1848626] using some code contributed by him.
Edit 2: Added the age of the difficulty rating to the panel header in 0.6. Any ratings made before 0.6 will show as (automatic). If you change the difficulty to something else and back, the rating time will be stored and displayed as (0 days ago).
Edit 3: Added an import/export feature in 0.7. Please be advised that import will overwrite your existing notes. So please for the love of god do an export first and save it somewhere before you try importing anything. If you manage to screw everything up, you can import {} and that will reset your notes.
Mentions: miros [1848626]