Is there any software like 'Network Magic' for Mac?
Well, there are some network monitoring &amp; management tools for Mac OS X you may want to have a look at (although I haven't found a direct hit I guess). For example, 
Casper Suite, InterMapper, IPNetMonitorX, Lithium 5.0, AutoScan-Network, 
DeployStudio, ...

To see who is on your network you may use Ntop.

Since Mac OS X is a Unix-based operating system, there are also command line tools that allow you to manage other Macs remotely via SSH. For example, systemsetup, networksetup and screencapture.

And, last but not least (as already pointed out by mrbitch), there is quite some 'Network Magic' functionality that ships with Mac OS X by default (see, for example, the 'Sharing' system preference pane).