According to a story in The Telegraph (UK), here are the top 10 authors by earnings for Jun 1 2007-Jun 1 2008:

1) JK Rowling £160 million ($282.5M)
2) James Patterson £26.7m ($47M)
3) Stephen King £24m ($42M)
4) Tom Clancy £18.7m ($33M)
5) Danielle Steel £16m ($28M)
6) John Grisham £13m ($23M)
6) Dean Koontz £13m ($23M)
8) Ken Follett £10.6m ($18.7M)
9) Janet Evanovich £9m ($16M)
10) Nicholas Sparks £8.5m ($15M)

It appears that rags-to-riches seems to be useful in becoming a well-paid author:

J. K. Rowling went from being on the dole to the highest paid author in the world. In fact, last year, she earned approximately 6 times more than the next closest writer on the list! Not only that, but her total income for the year actually comes out to more than the other nine authors earned when added together. Harry Potter is definitely magical in more than one way!

Another current trend looks like fiction sells and sells well. All of the top 10 authors specialize in writing stories and novels, although a few have branched off into non-fiction, too. (Nichols Sparks put out an autobiographical book, Stephen King has written books about writing, and Tom Clancy has co-authored books about weapons and war, just to mention a few.)

Given the names on the list, it also seems that people are currently biased towards reading and buying mysteries, be they based in the espionage, romance, thriller, crime (or magical) genres. How long that trend continues, it’s hard to know. The economy drives book sales to a big degree – with what’s going on now, what are you interested reading or think people will want to read? (Personally, I’m just trying to get my hands on the rest of the Harry Dresden books – magical mysteries are my poison for now.)