The best sample code I can recommend is in any of the social plugins we distribute with JFBConnect. There are about 9 social profile plugins available in the download zip file for JFBConnect that you can go through for examples. They won't all be installed on your system as JFBConnect only installs the plugins that would work for your site.
I wouldn't recommend overriding that function. I'd recommend overriding the onRegister() function or one of the functions it calls, like createUser()
Beyond that, if there's something specific you're looking to do, let us know, and we can help provide suggestions. The simplest plugin is probably the K2 one, but, again, I'm not sure what you're looking to do.
Finally, please be patient when you ask a post. We try to get to all posts quickly, but bumping a post after 3 hours isn't really necessary to speed things up.
Thanks,
Alex