It's odd to think that we're only a community of 5000. On Reddit I rarely feel the impression(other than when the god damn servers go down) that there are literally ~100,000 people browsing along with myself. I think it has to do with:
1. Tighter community.
2. Active Users. I'm not sure I've seen a more active community for its' size. Of course, that might be a little bit more easy for me to see, considering the site is based around power users.