For example, this season Kannagi was tops. Was it the most popular anime? Probably not; Nodame's the one that broke a viewing record for its late-night time slot...but Kannagi's recent controversy about its heroine's virginity (or possible lack thereof) probably gave it an added push. Besides, sequels like Gundam 00 and Nodame weren't even included.
That said, it's kind of fun. Kannagi had 107 threads, with Toradora! only a little behind at 95. Third place went to Ga-Rei Zero, which is interesting because I haven't seen a ton of buzz about it among western fans, and Toaru Majutsu no Index and Kurogane no Linebarrel wrap up the top five.
Of course there are plenty more anime that were discussed, but once you get out of the top five you get down into one-digit entries (like poor Bihada Ichizoku, a series about two sisters competing in a beautiful skin competition, which had only two threads). I'd be really interested to see a version of this list that DID include Nodame and Gundam and the others of their ilk, too.