On my other site today a friend and I put together a little project as a goof. However, since she and I are both relatively experienced bloggers, we know that a little promotion can be the difference between a goof that nobody notices and a goof that people blog about and pass around. While it's not exactly manual labor, it takes effort to investigate which sites might be most likely to link to you, most likely to bring you good traffic, to contact them, pitch to them why they might like your idea, and then maniacally monitor the hit counts.
This has been going on for a few days and it's been fun but exhausting, too. And this is for a couple of lousy blogs. I have sad news for you, authors: it's much worse when you're trying to move real books. Read about what authors need to deal with to market themselves at this article from the Miami Herald.