[eluser]esra[/eluser]
There is a Khaos ACL library by neophyte described in a thread within the Ignited Code forum. It is similar to the phpGACL library with support for AROs, ACOs, and AXOs. There is no documentation, but you can use the phpGACL documentation. AXOs are implemented without using nested sets, but the basic concept remains the same. This is a fine-grained ACL solution.