Google’s first MacOSX application, available at http://toolbar.google.com/gmail-helper/index?promo=gdl-en.

Interesting things about it from a Cocoa developer’s point of view:

• Google has chosen GG as its own Objective-C prefix (see ChooseYourOwnPrefix).
• Plug-ins can be created as LoadableBundle***s that are placed in ~/Library/Application Support/Gmail Notifier or /Library/Application Support/Gmail Notifier. See the GGPluginProtocol.h header in Gmail Notifier.app/Contents/Headers for more information. (Hmmm… I’ll try my hand with it and the Growl framework if I have time.)

– EmanueleVulcano aka millenomi