There is a long list with witnesses although they are not all active. A problem in average we can only see a few. I tried to load more pages but I can only see two and the list with no longer witnesses isn't very charming. It would be good if we all could see an overview of the active witnesses keeping the blockchain running, since that is what they do even if they do not generate blocks. Next to that, they are active in different ways. From development (can be way too many) to other things like upvoting Steemians and organising contests.