This page has the guidelines for spanking story sites Bethany's Woodshed, The Spanking Corner, and Romantic Spankings.
Not only focused on spankings, The Dominant's View is open to fiction stories and non-fiction articles (and art).
In sad news, WickedlyYours is closed to story submissions.
And I should spank you if you don't know this: The Erotica Writer's Guide to Creating the Perfect Bio. (But if you read it now, and *do* it, I won't need to...)