Maxim Jakubowski identifies (link above) the writers' blogs he follows "religiously": Neil Gaiman, Belle de Jour (two obvious choices, not my cup of tea), Marie Phillips, Meg Gardiner (must try, didn't know she blogs), John Connelly (also highly recommended by Crime Always Pays, so worth a look-- though I loved his first two or three, have not enjoyed his last few books) and a couple of others (links at the post above).
So, which writers' blogs do I follow? Not many, truth be told. I've looked at quite a few writers' blogs but they don't sustain my interest because they tend to be too self-regarding where their own books are concerned. Most of my favourites are readers' blogs, because they aren't trying to "push" anything. But one or two writers have blogs that I really like -- I've already mentioned Crime Always Pays (Declan Burke), to which I add Michael Walters, Susan Hill, Clare Dudman, Prairie Mary, Brian Sibley, Debi Alper, Henry Gee, Bill Liversidge. These are all blogs that I very much look forward to reading every night or every other night. Why is this? Well, they are not primarily to promote their books, or if they are, they do so in such an amusing and individual style that you don't mind or feel pressured. I like them because they are written by such sparkling, interesting people who have stimulating things to say and can put those things well. The fact that they are authors of books is, or can be, incidental. Have I missed any? (No self-nominations, please ;-) .)