Current method of category choosing while creating the topic includes two methods: by scrolling down the list or typing in the search field, which is amazing. What about extending the search capability and also include the category descriptions?
If category “hosting” has the words in description like “servers”, “cloud” and so on, then typing these words in the search field also will show the hosting category.
This feature could be beneficial for the large forums with lots of categories.
p.s. Discourse fantastic search feature needs more love :D.