An excellent forum for people who enjoy spankings and find them erotic is the Spanking Den.
From the fine folks at Sexuality.Org, a primer on warming your partner's bottom. "Details on Giving & Getting a Good Whooping."
If you would like to learn more about spanking each other in sexual way, consider a column on the subject by writer Diana Cage. It is on the Good Vibes website. "How To Spank Your Lover for Pleasure!"
Here is not one, but TWO books worth of spanking stories from Rachael Kramer Bussel! Naughty Spanking Stories
For spanking fun, you can't go wrong with Adventures of Spanko Girl.
Here's a list of spanking terms.