Valentina for REALbasic - Create fast and powerful database driven applications using REALbasic. It allows to drag easy to access classes of object-relational database directly into REALbasic project. [Shareware] - http://www.paradigmasoft.com/product/v4rb.html
Building REALbasic plug-ins with MPW - A kit for building REALbasic plug-ins with Apple's free MPW. Uses REALBasic Plugin SDK 4.5a1 and later. - http://www.pmpfr.co.uk/RBonMPW.html
Alfred Van Hoek's REALbasic Plugins - Many REALbasic Plugins, including RBPluginPlunger, HTMLRendering and other great plugins - http://homepage.mac.com/vanhoek/