Obviously not counting "system" communities like news, paindmembers, etc
wtcdisaster
It was created 11th September at 08:43:19, it has 187 members, 264 posts, and 880 comments. For every hour it's been in existence, on average, 9.35 members joined, 12 entries were made, and 40 comments were posted. That's a huge growth-rate.
I thought it was monumental that LJ is a huge resource for news, when so many other official news sites just buckled under the strain. LJ must have suffered more hits and more DB accesses then before (probably even since records began?). I'd be interested in seeing the stats for the 10th September, and the 11th September as a contrast.
Just want to say "well done!" to Brad and the other developers who have made sure LJ outages aren't as common. I'm sure this latest stress-test has proven, for now, LJ is very stable. Hurrah!