A lot of people regularly report (=flag) spam and other unwanted posts/topics and thus contribute to keep ask.fedora clean and compliant.
We already talked about badges for solutions and marking solutions and many other contributions.
But I would like to add the idea of a badge for reporters of spam and unwanted posts/topics to the list:
Such a badge shall motivate and reward people who keep their eyes open and report if they see something that does not belong here. At the same time, we should not motivate floods of flagging: therefore, I suggest to not create a badge for the flags, but for the approved flags (so flags that have been approved by moderation).
Just to shed some light on the topic (and on the people who contribute a lot this way) 
I am aware that other tasks need to be tackled before we implement further badges, but it might be already worth a discussion 