On the Django IRC channel, I was helped through some resources for replacing the auth systems's User model with my own extended version. Here are the notes I made. Note that it was 2:30 am local time, beware hacker fatigue syndrome.

[02:18] <harmless> phew, that was NOT easy
[02:18] <harmless> note to all:
[02:18] <harmless> if you wish to replace the auth User model with an extended version, you must do the following:
[02:19] <harmless> 1. patch the createsuperuser function in core/management.py to catch ObjectDoesNotExist rather than users.UserDoesNotExist
[02:20] <harmless> 2. ensure that your model's META specifies module_name = "users"
[02:21] <harmless> 3. provide a _module_create_user function that does all of what django.models.auth.User's does, plus inits your new fields
[02:21] <harmless> 3 a. note that it's easier to use keyword arguments here, as it's not clear what the field order is when extending a model
[02:21] <harmless> 4. wipe your entire database every time you make a change.
[02:22] <harmless> and that pretty much did it for me, i've got my own user class being used successfully for auth and admin, and it's a single nice class in the admin interface.
[02:22] <harmless> so maybe next time i need to do this, this transcript will be a quick google search away :)
[02:25] <alect> perhaps you should wikify it
[02:35] <paulproteus|lapt> I'm with alect on this one. (-:
[02:36] <harmless> well, i'm not sure it's wikiworthy at this point
[02:36] <harmless> it looks like it's changing right away anyways
[02:36] <harmless> but i'll paste it in with a "late night hacking" warning

Missing here is step 2b, ensure that your model's META specified replaces_module="auth.users", and step 5, you must copy the original models' entire META.admin section if you wish to change it at all.

Here's what my model looks like at this point:

class User(users.User):    
  gamename = meta.CharField("Game Name", maxlength=100, blank=True)
  url = meta.CharField(maxlength=100, blank=True)
  description = meta.TextField(blank=True)   
  # SNIP a few more extra model attributes

  class META:    
    replaces_module = 'auth.users'
    module_name = "users"
    verbose_name = _('User')
    verbose_name_plural = _('Users')
    module_constants = {
      'SESSION_KEY': '_auth_user_id',
    }
    ordering = ('username',)
    exceptions = ('SiteProfileNotAvailable',)
   
    admin = meta.Admin(
      fields = (
        (None, {'fields': ('username', 'password_md5')}),
        (_('Personal info'), {'fields': ('first_name', 'last_name', 'email')}),
        (_('Extended info'), {'fields': ('gamename', 'url', 'description')}),
        (_('Permissions'), {'fields': ('is_staff', 'is_active', 'is_superuser', 'user_permissions')}),
        (_('Important dates'), {'fields': ('last_login', 'date_joined')}),
        (_('Groups'), {'fields': ('groups',)}),
      ),
      list_display = ('username', 'gamename', 'first_name', 'last_name', 'is_staff'),
      list_filter = ('is_staff', 'is_superuser'),
      search_fields = ('username', 'first_name', 'last_name', 'email', 
                       'gamename', 'description'),
    )

NOTE

If you're using development django, these steps change a bit.

• you won't need to modify createsuperuser (step 1 above)
• you will need to change password_md5 above to just password anywhere it appears in your model's META - specifically, in admin.fields