I would like to suggest a clearer notification if a Tag is used that doesnt belong on a particular site. For example, on Stack Overflow the ffmpeg tag states:
"questions about using the FFmpeg command line tool should be asked on Super User."
An orange pop up box alerting anyone who adds the ffmpeg tag, suggesting to the user to move their question to Super User, would help to reduce the number of off topic questions on Stack Exchange.
Just an idea.