It takes more than just a pretty face to launch a thousand ships these days, and the same goes for a dozen bestsellers. As I write these words on the morning of October 28, Joe Konrath has 5 of the top 17 titles on the Kindle Store Movers + Shakers List, which by definition also means that he has at least 5 titles in the Top 400 overall in the Kindle Store.
How does he do it? He's not just the hardest working man in the book business, he's also, by my lights, the smartest.
Every author and every publisher would do well to go to school on the very specific steps that Joe takes to cross-pollinate his various titles and brands with his other work and even with novels by other authors. And Joe makes it easy to learn with excellent posts like this one on his blog, A Newbie's Guide to Publishing. If you have a Kindle, subscribing to the Kindle edition to have his frequent posts pushed directly to your Kindle will probably be the wisest use you could ever make of 99 cents a month.
By the way, the same principles of cross-pollination also work well in association with Kindle Nation Daily sponsorships. Authors like Paul Levine and L.J. Sellers have seen a powerful "halo effect" benefit where a sponsorship for one title also paid off dramatically for other books or series. In cases like these, the author has a distinctive brand, a number of highly regarded books, and a willingness to price creatively for maximum marketing impact.