I would like to propose to introduce per-category factors that would affect all components of a topic’s ranging system, depending on what category it is found in. The same can be applied to tags, btw.
Even though our forum is specialized in goat farming, cheese making and also aimed at milk addicts, there are topics in the “offtopic” category that sometimes get too much attention and thus get quickly to the top in the
/top page. Still, I’m unhappy about making such non-professional topics to be shown above all other topics. This makes an impression that our forum is not so professional.
That’s why I’d assign a factor of 0.9 or 0.8 to the “offtopic” category.
Of course, the factor should be always 1 by default unless you explicitly enter a value other than 1.