Ruby growl
For anyone who uses Growl for event notification on Mac OSX and who wants to receive notifications from a Linux machine (eg: a local server), take a look a Ruby-Growl. Pretty simple to set up and works fairly nicely.
Example CLI usage:
growl -H 192.168.1.x -t "Server ready" -m "The server has finished booting" -P ******
It might be nice to be able to do a general network broadcast but I suspect the security implications mean you need to use something like Zeroconf/Bonjour to get a list of available clients and send notifications to each one with an associated password.
I also hacked together a quick Internet>LAN bridge for receiving notifications from a remote web server using Java some time ago but it was a bit rough round the edges so I might redo it with Ruby at some point.
