Why don't the leaderboards update when guests (who are NOT members) view a blog, event, photo, video, etc? This is give a more accurate view of which activity is well liked members AND guests.
Also if you can keep count of visitors to each activity and display them as well on the leaderboard, that would be helpful.
Different people have differnt ways of using their website. I keep it open and only require people to sign up once. After that they can read everything in the website without logging in. So I really need to know the popular actitivities of non sign ons as well.