I see the same thing. After every episode, I always check the LJ watch post because of the interesting discussion there, and the kink meme has so much great stuff on it. Tumblr is great for Pixiv stuff and I really enjoy all of the gifs I've seen on Tumblr, though, so I think it has it's own unique purposes. I feel that with T&B fandom, LJ and Tumblr all help to create a really full fandom experience by doing different things and complimenting each other.