Beyond the excitement of signing the contracts and being recommended by Oprah (I wish!), there's a lot of work involved in getting a book to market (and, with, luck, making it a success). I've previously mentioned working with the artist on a cover design and working with the editor on the galley proofs and to decide on the final title of the book.
In addition, there's creating a short blurb for the jacket to describe the book in such a way that a casual browser just has to buy it. And there's selecting a longer excerpt to represent the book on your web page. Not to mention creating said web page in the first place (and, natch, a blog). And writing an author's bio that's both informative and somewhat less dry than a 5,000-year-old mummy's throat.
But that's just the beginning. If you're not lucky enough to sign with one of the top publishers--with enough buzz behind your book to warrant a big-bucks promotional campaign--you as the author are in for a lot of work doing self-promotion.
I'm still learning about this, but there are many aspects to promoting yourself and your books. There are the little things, like printing up bookmarks to hand to people. (The bookmarks contain your cover art and something about you, the author.) Also, letting everyone know you just sold a book--including people in all the chat rooms, discussion groups/forums you frequent, as well as all your IM buddies. If you belong to writer's groups, book discussion clubs and the like, let them know as well.
Unless you're sure that every bookstore in the known universe will carry your book, it doesn't hurt to drop into all the local bookstores and offer to autograph all the copies of your book that they order. Getting a few copies in the door (especially if they're posted with a sign indicating that they're autographed), can't hurt. Who knows, you might sell a few.
In addition, you might email all the websites and ezines you can find that do book reviews and ask them if they'd review your book. You might be surprised at how many will trade a review for a free book. (It doesn't guarantee a favorable review, but when you're an unknown writer whose book sales are effectively zero, a positive review will help far more than a negative review can possibly hurt you. (You can't have negative sales, right?)
As for book signing, interviews, talk shows, etc., you should be so lucky. If it happens, sure, it'll be a grind, and after the first blush of excitement fades, not much fun. But it sure beats being ignored. Right?
Mark. (Still waiting to see the final cover design.)