Addons » Download Management(Formerly Local Install) The primary goal of this extension is to provide the tools needed to install and manage extensions and themes locally and tons of other features.
Note: With Toolkit 6.0 Auto Archiving is fully working in Firefox 2.0 and temporarily disabled for Firefox 3.0, fix coming soon.

See also
Image ToolbarSingle-click access to common actions for images (e.g. saving, copying, printing). This extension is intended to provide a replacement for the equivalent toolbar in Internet Explorer.
TiX Now!Ti's eXtension v1.0...
Download SortAutomatically save downloads to different directories when using "Save Link As..." or "Save Image as..."
Download statusThis add-on replaces the standard download text of Firefox 3.* with some more detailed information. It displays the total download speed, the remaining size, the total number of files and the remaining time of your downloads (including DownThemAll!).
Automatic Save FolderThis add-on will open the File Browser at the right location, using simple filters on the downloaded file.
The filters are based on filenames and hosted domain's name.