I recognize that this is old news for some, but I've finally had reason to use the Growl module for Drupal. Getting fast reporting of logged errors is really handy without having to flip through tabs to find out what thing I just broke. There are not any instructions with the module, but it is easy enough to get it up and running. The real trick is making sure that you have the grownotify script in the correct place. Using this on your localhost is probably the simplist way to go given you will need to negotiate firewalls and IPs if you are trying to debug a remote server.