Can I allow users to add themselves to certain change usergroups? i.e liverpool fans

[kh99]

What you could do is create custom profile fields, then check those fields instead of the user group, like:

if ($vbulletin->userinfo['fieldX'] == something) $styleid = x;

To answer your original question, you could use usergroups if you wanted. You could create a page with the options, then have a script to change the user's group based on what they choose.