This may be a project I get back to. Here is a summary of major African diaspora religions. I've done a fair bit on Vodou and Santeria over the years, but I haven't yet ventured beyond those two. These are religions that formed within the African slave population in the New World, based partly on tribal African beliefs (often mixed together as people from multiple tribes would be deliberately sold to a farm) and partly on the Catholicism of the owners. Native American beliefs sometimes contribute as well.