Windows only: Google Wave has a lot of potential, but it's also another inbox to keep track of. Google Wave Desktop Notifier is a small system tray application will let you know when you've got new messages in your inbox.
We've featured a Google Wave notifier before in the form of a Firefox extension, but if you prefer a non-browser alternative, Wave Desktop Notifier will do the trick. This handy little program gives you some pretty detailed notifications when you receive new waves &mdash ;it checks your inbox every two minutes, and then shows you your last received reply in a notification (as well as how many unread waves you currently have in your inbox). In addition, you can access your five latest unread waves from the system tray icon, or just navigate directly to your inbox. I'd love to see it give the option of using Growl for Windows instead of its own dedicated notifications, but it's certainly a great addition to any Wave user's system tray.
Google Wave Notifier is a free download, Windows only.