Platforms, networking, blogging and Twitter for authors - resources

I'm doing an event on Twitter for the Society of Authors in London today. And a talk about blogging and Twitter for authors at a conference in Peterborough at the weekend. And one about Twitter and blogging at a dinner for senior people in publishing a couple of days later. For the benefit of the participants at those, and also any of you who would like all this info in one place, I have made a