administrative notes

I would like a way to take notes on pages that are only visible to certain roles. Adding a hidden field could do this but it's a lot of overhead, doesn't properly separate content from notes, and would apply only to content types.

For temporary content - "Hey we should do something else with this page, maybe such and such" - an input filter for hidden text would be perfect-- even something that really hides <!-- HTML style comments --> and displays them nicely.