Net Drive Status is an utility that runs in the background on the Mac OS X status bar and visually reports the presence of a specified network drive location. If the network drive is available a green icon is displayed, otherwise a red icon will be shown.
Handy if you need immediate feedback whether your network drive or even USB drive is properly accessible. This prevents problem when launching your favorites application if your external resource is not available. May also be used in combination with an iTunes library on a network volume, it will then warn you when your iTunes library is not available so that you can prevent iTunes, by not starting it, from automatically changing to the default, local, library location.