Today is the day, Nightborn (aka the Darkyn returns) is officially on sale. Also officially on sale today, the start of a promising new series by Seanan McGuire,
Discount Armagedden, the newest Cal Leandros book from Rob Thurman, a new Alpha/Omega book from Patricia Briggs, hot romance from Stephanie Tyler and Jaci Burton. It's like the publishing fairy brought out all the goodies on the same day to make up for my month of sick people and teething baby.
Since I naturally want all my favorite series, fascinating new series, and great romance to continue to be available, I tend to preorder so that my purchase counts towards the all-important (to publishing) sales numbers of the first week. This is also a great time to descend on the local bookstore and ask for the book if it isn't visible; sometimes this prompts somebody to remember that box in the back that didn't get opened and once on the shelf, somebody else can discover it. Request a copy from the library. And so on.
There are many ways to support your favorite authors. Buy the books, borrow them, talk about them, recommend them to a friend. It all helps to ensure that the next book happens, that the series doesn't get dropped. Before I knew anything about the business I had no idea that something as simple as a library hold placed or a "here, you've got to read this" had anything to do with whether or not the books continued to come out. It matters.
For Nightborn and Discount Armageddon in particular, which had physical books shipping well ahead of the official on sale date and thus actually penalizing the authors on their numbers, reader demand and word of mouth can make an enormous difference. Love paranormal romance and urban fantasy? Give these a try. If you like them, recommend them to a friend.