Once you get your book published, you'll need a phenomenal website to help publicize it. I've been lusting after the websites done by Authorbytes. They do online publicity for authors, including website design.
You can set up your own website before you get published, but once you get your contract signed and your advance deposited, I recommend investing in a professionally designed website.
I love the ones Authorbytes did for Doreen Orion's book Queen of the Road and Sam Walker's Fantasyland. They do sites for both fiction and nonfiction authors. Check out their portfolio to see more examples. I'm betting they're pretty pricey, though. They've done websites for some uber famous authors.
If you can't afford one of theirs, they recommend checking out the author website templates at Authorsguild.net, but you have to join the guild. Dues are $90 per year. Check out this example from children's author Toby Speed. Looks professional, heh?
Plan for promotion!