[PHP] User/Group rights system?

Hello, Does anyone know of an open source "user/group" based permission system built with php/MySQL? That is, the effective rights for any user on a specific secured object are computed from various permit/deny permissions assigned to the user or any of the groups he/she belongs to. PEAR::Auth s

[PHP] Clean Open Source PHP extranet app?

Hello, I am looking to create a simple "extranet" type application similar to http://www.basecamphq.com/ written by 37signals. Basically I just need a way for users to share files/projects/messages. In fact, I would just go ahead and pay for Basecamp except that it's closed source and it's onl