Gmail Notifier + Growl
Recently, Google was kind enough to release Gmail Notifier for OS X. This seemed like a better alternative, long-term, than what I had been using (GmailStatus), since it’s, made by y’know, Google. The only thing lacking was Growl support. It turns out that Gmail Notifier can use Plugins, and sure ‘nuff one of the first plugins available is Gmail+Growl. Marvy!