This is something I have needed for a long time, so staff keep all user notes in one place -- their profile. @au lait fixed a couple of issues I had super quick (24hr turnaround), and I am really impressed with the ease of use this provides to help manage members. If you have a staff forum with user issues all over the place, I highly recommend this instead.
This will replace the [el] User Notes system on AVForums.com when we go live with Xenforo 2. I've tested this on our XF2 sandbox and it works well. @au lait also supplied an SQL query to migrate our 200,000+ existing user note records. Grateful that this addon exists as its functionality is essential.
Simple but very useful little addon that fills a need not met by existing bookmark addon's or by simply marking threads as read, etc. Users can make notes on threads that they can see when browsing threads, allowing them to see at a glance some pertinent information about a thread, reasons why they might or might not want to revisit it for whatever reason, etc.