Snarl is a great little Windows clone of Growl (an OS X tool for displaying notifications from applications). It has a window message based API that you can use from any language on Windows. However, I'd like to use it to alert me when things happen on my coLinux VM -- when compiles finish, rspec finishes its run, things finish downloading, etc.
I've made a little Python script that listens on a TCP port (10942) and 'snarls' text it receives from connections via PySnarl.
I've thrown it up on github if anyone else would like to do the same sort of thing: tcpsnarl.
Note that this is NOT the same as Growl's networking protocol, which may one day make it into Snarl. It's a convenient solution in the meantime, though.