I have recently completed a small and very hacky alpha release of a Dynamic Agent Management tool for FreePBX v2, based on the AddQueueMember dialplan application and devstate function. This builds upon the work of several others in providing a dialplan-only replacement for the AgentCallbackLogin functionality of Asterisk 1.4. This module generates the dialplan code and agent relationships.
This is tested only on FreePBX 2.6 running Asterisk 1.6.1 and 1.6.2. Some corners were cut in churning out this project quickly. A slightly non-standard ways of generating dialplan code was used, as well as a hacky method of detecting agent state. Agent passwords are not supported at this time.
I have provided a more complete description of the module and its limitations here:
I hope this helps out anyone that is looking for dynamic agent functionality within the excellent FreePBX GUI.