Spiffy is an advanced Gmail notifier for Windows, it's free and completely customizable.

Changelog:
added russian translation (Thanks Vladimir)
added polish translation (Thanks Adam)
added more height options for custom alert (Thanks chorre)
fixed bug starting thunderbird email client (Thanks Jack)
fixed bug occurring when receiving mail from unknown senders

Program Information Category: Tools and Utilities Type: Free Version: 0.5.4 Size: 341KB Works on: Windows Product page: here