I was looking around for hours the other day to find out how to add a custom meta box to one of my plugin settings pages. It's quite simple and well documented in many places on how to create the meta boxes for a post/page edit screen, but not for a custom plugin.
After hours of reading and testing I finally made it work and thought I would share my findings. http://thewebsolutionprovider.com/wordpress/wordpress-tutorials/custom-wordpress-meta-box-for-your-plugins/