If you are a Firefox user, you may have noticed that yesterday Mozilla released an updated version of the browser. This new update includes a number of security updates and graphics optimizations, but in addition OS X users are now able to monitor downloads directly in the Dock.
When you download a file in Safari or prior versions of Firefox, the download process can be followed by going to a special Downloads window, where you can monitor overall and individual download progress; however, this requires you to keep such a window open. Even though Safari's downloads toolbar menu will show an overall progress bar, this still requires the menu to be visible on screen.
With Firefox 22, Mozilla has added a download progress bar to the Application's Dock icon, which will give you a quick overview of your active downloads without needing a Firefox downloads or browser window open in front of you. The progress bar does not represent individual downloads, but instead shows a the cumulative progress of all downloads collectively. Thus, if one is stalls, the progress bar will advance while the others continue, but then will halt when the one that's stalled is the last download left.
While a small feature, this should add a small bit of convenience for Firefox users, especially those who regularly download large files or many files at once.
Firefox version 22 should download and install automatically for those who are running Firefox 21 or earlier, but can also be downloaded directly from Mozilla.