Although it's worked both ways, I think blogging does more sales harm than good in my case. Some authors annoy me* and others have a blog voice that's so similar to their book voice so that I think "author" instead of "story" when I read the book. I can think of only one author where I read the lj, deliberately hunted down the book, and loved it, and the book was non-fiction and so a different kettle of fish.

Getting recs from people on lj is another matter. I do that quite a lot and have found some fun stuff.

*Politics being one example. It's not that I stopped buying someone's books because they voted for the Satan candidate (good, smart people on all sides!), but I hesitated with a few because they were so preachy that they stopped being The Author and became The Political Organizer, and I had less interest in the latter's work or in supporting their whoring of their poor stories. This may be a hopelessly 3rd party view though.