[eluser]mglinski[/eluser]
There are a number of prebuilt auth libraries available(freakauth, etc.).
I code my own, based on user profiles, and heres how i do it:
2 DB Tables: users, user_profiles
Users: self explanitory, include a row for profile ID
user_profiles: setup each row as a permission setting, one being a user access level.
On login grab the user profile and save it to session or retrive it on every page load. Then setup blocks in your code that will only work for specific permissions(rows in that DB).
Enjoy
-Matt