I don’t know what others are doing, but as Ben suggests, I started out by adding a table to the data base to hold the additional user fields that contained a foreign key from SFSuser.  As Ben would probably not recommend, I modified the SF user maintenance dialog by adding a tab to maintain the added info along with a BO that mapped to my new table. It looked and worked great, however keeping my version of Role Based Security in sync the SF release quickly got old. I ended up building my own “Additional User Info” maintenance screen that has the same look and feel of the SF user maintenance dialog. On my main form I have a User maintenance menu with “Security” and “User Info” sub menus to bring up the proper dialog.

I also added some logic to AppMain that checks to make sure the additional user info fields are populated when the user logs in and exposes those fields via public properties of a static class.  

-Larry