Firefox with Greasemonkey: Gmail FavIcon Alerts turns Gmail's tiny address bar and tab icon into a multi-function ambient alert system, showing an unread message count and changing colour for new events, like chat messages. Consider it an upgrade from the previously featured Gmail Unread Message Count script, with similar handy features but a bit more functionality. Its favicon—the little graphic that shows up on the left-hand side of bookmarks, address bar locations, and tabs—changes colours to indicate read/unread/chat status, and shows a count of unread messages, capped at 10, in a little text tag.
I'll let the script author explain the icons himself:
- A Blue icon lets you know you have unread mail. New to 2.6, the number of unread messages is indicated in the icon!
- A Red icon means you've read all your mail (or, at least, clicked on them all).
- A Flashing Orange icon means someone has sent you a chat message.
Gmail FavIcon Alerts is a free download, requires Firefox and the Greasemonkey extension.