This plugin is exactly what I needed for a database of users, more than likely it's what you need as well. It took a bit to set up and configure properly, but once I did it worked even better than I could imagine without having to fiddle with code to get things working right.
Additionally, xnau is a very responsive developer. He responded to my troubleshooting request within 12 hours and was as helpful as he could have been.
I'm looking forward to the new features of this plugin.