How about making it possible to set up bounty on someone else’s question?
I would like to have a feature that will allow me to assign a bounty to an old question (asked by someone else long time ago) and reanimate the discussion in this way.
Today I found on SO question asked a few weeks ago. Of course I can ask a new question with slightly changed definition, but this will lead to lot of duplicated questions. I suppose we need to encourage adding more information to existing questions if they are clearly formulated, rather then creating new ones. There should be a way to attract attention of SO community to the question that seems to be important.