Out of Date, but still solid for finding IP and MAC addresses
Airport Utility 6.x does not list the MAC addresses of eithernet attached devices, but iNet does. iNet works great at identifying what is on the network, its IP, and its MAC. Other than that, it is tragicly unaware of most Apple devices and the interface shows it has been a long time since it was updated. For $8 it was worth it for me. I just wish it could do more and be better.
Update 10.9: Release notes indicated improvement in the vendor dB. I checked again and it did not know about an Airport Extreme as an apple product, nor that my Netgear device was a NAS, my Hewlett Packard device was a printer, nor that by unknown device is a Foscam camera. Still worth $8, but I still wish it was better.
mayhem9 about
iNet Network Scanner