Angry IP scanner is fast and friendly network scanner for Windows, Linux, and Mac. It is very extensible, allowing it to be used for very wide range of purposes, with the primary goal of being useful to network administrators.
The next milestone before the 3.0 final has been released, containing many small improvements and bug fixes.
Most notably, it fixes compatibility issues with MacOS Leopard Java Update 2 and newer, adds command-line support, provides stock icons for buttons on Linux, adds the possibility to add comments to scanned hosts.
Get it from http://www.angryziber.com/w/Download