To be fair, the current flagging system is heavily under-utilized on my site. Users don’t seem to understand that flagging a post is the desired method for them to help to “moderate” the forums.
It’d be nice to be able to edit the flag reasons (globally) to in/exclude specific reasons or include category-specific reasons (a category for research might have “citation needed”).
Additionally, the post editor itself on the flag options window is terrible. I’d highly prefer to use the full editor, and never have to PM a user about their post from the options screen (where I can’t even see their post because the options window is covering it). If I could quote specific parts of their text to discuss it with them, insert links easily, and not be limited to 500 characters (or whatever it is), that’d be a big improvement.
The system I proposed would expand on already-existing features, making use of “whisper”-like hidden-post to discuss the flagged post in the same place as where the flagged post resides.
EDITS: Basically some of this is expanding on the ideas from the “Create custom flags” thread, which I just read.
I like some of the concepts/mockups shown in the “Some ideas for improving the flagging dialog”, but all these mockups still show using the options window (directly) to send messages or leave ‘notes’, which is bad, for several reasons (IMHO).
It lacks a full text input editor, and also because the “something else” PM moves discussion of a post away from the post itself (to messages/inbox), when you in fact want the person receiving the flag to be where his flagged post is, for him to edit it immediately (which is fixed by having a “whisper” style private-reply appear inside of the thread).