1) SONRIS Louisiana Department of Natural Information web site - The site is frustrating in a lot of ways, but there's a LOT of good info there once you learn how to access it. www.sonris.com
Interactive maps is the most "interesting" part. It's also useful for non mineral related mapping info.
2) Kassi Fitzgerald's Natural Gas Leasing Basics
3) This leasing checklist is for Texas, but many of the ideas may be valid elsewhere. http://www.tlma.org/oilgasleasechecklist.pdf