There are heaps of guests always online - 90% of these come from either referrals from other forums or from search engines and most of them are viewing threads.
This thread has 65,000 views and most of them are from searches for 'skyrim kematu'.
You were viewing the forum at off-peak, right now there are on average 500-600 guests online at once. (although Google analytics real time reports only 200 guests online, not sure what XF does it in. Past 5 minutes or so?