Just spent the day figuring this nifty trick out.
If you've found this page then you probably spent time in the Articulate forums and blogs reading about how the only way to get the user name is to have them answer a survery question at the beginning of the quiz.
Forget that! ha!
Here's what you do.
1. Using flash create a new movie clip and rock this code in your actions panel:
import flash.external.ExternalInterface;
var username = ExternalInterface.call("parent.GetStudentName");
studentName.text = username;
2. On the stage add a dynamic text field and give it the name "studentName"
3. Publish the SWF
4. In your Quizmaker quiz edit the end page (for pass or fail) choose slide view, choose the insert tab, insert your wicked awesome SWF you just made.
5. Publish your Quiz into a SCORM package and import it into your LMS Wam. Pow. Bang.
6. Test it out, make sure it works, now edit the look and feel of your SWF and Endpage to perfection.
Stay Classy Internet.