3rd Party Software for AirPort Extreme Base Station?

Is there any 3rd party software which would allow a little more functionality and control of the device? Like the ability to see wired clients on the network, at the most basic? I have one of the new tower Extremes and Apple seems to have removed the option for downloading AirPort Utility 5.6 which I understand had much more functionality. Can any of you suggest some other software that offers more than the current iteration of AirPort Utility does? Thanks