IP Scanner – Displays machines, users, and IP addresses of Macs on your network.
IP Scanner scans your local area network to determine the identity of all machines and Internet devices on the LAN. Powerful results, yet easy and intuitive to use. Runs on OS X 10.5 Leopard and above. IP Scanner is designed to allow you to customize your scan results; once a device has been identified, you may assign it a custom icon and name to more easily recognize it at a glance.