In Firefox 4, the status bar was replaced with the "Add-on Bar", an empty, but customizable, toolbar. While some of the status bar items did find new homes, you may not have like where they ended up. There were also some nice innovations during the development of Firefox 4, such as putting progress/links/status in the location bar, which unfortunately didn't make it to the final release.
In Firefox 29, Mozilla decided it would rework the UI again, and ended up removing the Add-on Bar as well.
Status-4-Evar aims to bring back the Status Bar / Add-on Bar with the familiar classic status bar items, give you more control over the built-in Firefox features, and provide new alternatives.
The extension provides "Status Text", "Progress Meter", "Download Status", and "Legacy Status Bar" (Firefox 29+) items. These toolbar items can be moved wherever you want by customizing the toolbars. Behavior of the toolbar items, and other additional settings, can be controlled in the Status-4-Evar preferences.
This extension can also act as a replacement for the Fission extension. There are preferences to show links, status, and progress in the location bar instead of the toolbar items.