My favorite author is Vivian London. She writes a lot of different stuff, but it's always good. It's also really inexpensive!

I know her stuff is up on amazon, and I think it's at B&N too. link

Looks like I need a Kindle!

I really love Louisa Burton. link
I've probably mentioned her on here in another thread already, but her books are some of the only ones I reread over and over, since I actually find her characters and plots interesting unlike in a lot of erotica.

And it's not strictly erotica, but Nancy Friday's books of people's sexual fantasies are also on my keeper shelf. There's a whole range of stuff in those!