[eluser]Gromozeka[/eluser]
Well, you are right, user_profiles from original Tank Auth isn't too useful. It's empty and there is no enough methods to work with it.
I added it to the library as a place where all user data should be stored in. These data may vary from project to project, that's why I left it for project developers, to fill this table with necessary fields and data.
So if you want to add some fields about your users then you just need to put them in 'user_profiles' table and write necessary handlers.