Google Reader Toolkit
Google Reader Toolkit is a notifier add-on for Mozilla Firefox. This extension places its' icon on Firefox status bar and notifies you if there are updates available on Google Reader.
It is heavily based on Bloglines Toolkit by Chad Everett.
This extension is still beta so don't be too strict.
Alternatively you can try Google Reader Notifier Firefox Extension by Mark B.D.B.
You can install extension using this link: Google Reader Toolkit 1.0.5.
This extension currently works only if you are logged in to Google Reader. I am using it with Gmail Notifier for Firefox (which does all login work). But it wasn't working with Gmail Manager.
My name is Yasha Davidov. You can contact me via e-mail . I'll be glad to hear from you.