Two more ideas:
(1) Since members have unique identifiers (e.g. "RS"), it shouldn't be hard (??) to set up a messaging system so that someone who wanted to send me a note privately could just post it to "RS" - rather than tying up a whole thread with a private note.
(2) And / or, what about a little box - on the main thread listing page - under the "Chat Room" link - where we could post the name of someone we had a message for. For example, if someone who was already in the chat room wanted to speak to me, they could post "Looking for: RS". Then when I saw my name up there, I would be very likely to drop in to the Chat Room & meet with them - whereas I might otherwise not visit just at that moment, & would miss the person who was looking for me. (Or if someone was lonely, they could always post: "Looking for: anyone at all!")
Anyway Max, you said you like challenges!
P.S. to Jon W: How tantalising for you to mention "another discussion forum ... nearly as interesting as this one" - and not post its address! Please do!!!