Update: Gmail now has a lab feature that does the same. Search for “Unread message icon.”
Shows the number of unread Gmail messages in the FavIcon in your Firefox tab.
Allows you to easily see how many unread messages you have without needing to switch back to Gmail. As the number of unread messages changes, the favicon in your Firefox tab or URL bar will change to show the number of unread messages you have in your inbox.
Features:
- Shows the number of unread messages in your Gmail inbox in your browser tab.
- Color of the unread message number in the icon glows brighter as number increases. “0” is green, “1” to “99+” get progressively brighter.
- Envelope icon flashes orange when you have a new chat message.
- Different Gmail icon colors for different Gmail accounts. Shows a red envelope icon by default, blue envelope icon for hosted (Google Apps for my Domain) email accounts. You can easily override these defaults, with 3 different envelope icon colors supported (red, green, and blue). Instructions on lines 14-18 of script.
Download: Script