Google Wave Checker Extension for Chrome
If like me you find Chrome gives you the most stable, enjoyable experience of Google Wave, you might also be pining for the notifier extension Firefox users get.
Well now Chrome has a neat little extension that does the same thing. Jeremy Selier has built a neat little plugin that shows you how many unread waves you have in your inbox. It checks every thirty minutes by default (at the request of the Wave team), but you can set it to check more frequently in the extension options.
Something that makes a sound, or pops up a notification box (Growl-style) would be even more useful in some circumstances (Firefox is still my main browser of choice). However, if you need a simple way to see new Wave activity without checking the window every couple of minutes, this might just be the thing.