The total varies, but that's the highest we have ever had online at once. The statistics are on the Portal page on the bottom of right column.
"Max Online: 1539 @ Wed Apr 18 2012 10:49 PM"
Since most of them were on one forum, I'd guess that some viral link was out there that brought lots of non-members to look at something specific. I'll have to look at the server logs to see what I can find.
Jim "Oldgas" Potts
Your host and moderator