Picking a location for all of your downloaded files is an easy thing to do.  All you have to do is go to Tools in the menu bar, then Options, then in the Main tab, pick your place to save your downloads.  What if you want all your downloaded .zip files in a folder named “Archives” and files downloaded from Mozilla.org to go into a folder named, “Mozilla Downloads”?  Then you need the Automatic Save Folder add-on for Firefox.

Right now I use my “downloads” folder as a catch all for all the things (audio, video, pictures and more) that I download from the Web.  From there I sort it out to where it needs to go.  If you want to add a few more favorite locations to save to from Firefox you can do so with the FavLoc addon.
FavLoc (short for favorite location) will let you set certain folders as favorite locations to easily download files to.  [...]

Now this extension delivers something I have never seen before. FavLoc allows you to set folders as “favorite locations” to which you can easily download. FavLoc menus will appear on the File menu (for saving pages), the context menu (for saving images and links), and on the download prompt. For those of you who have been needing a quick and easy way to send Web content to your PC in an organized way – this one is for [...]

Need to be able to add a quick bookmark inside of one of your folders via Firefox? Get the Add Bookmark Here Firefox extension and this dream can become a reality. This extension allows you to add bookmarks to any folder in the bookmarks menu like in Opera.
+ Learn More About Add Bookmark Here!

Don’t be fooled by the name, this extension has nothing to do with Digg.com. It is though a great tool to actually make that “Go” button a little more useful!
Allows you to navigate to parent directories in a URL and climb through subdomains (e.g. go to http://example.com/ from http://sub.example.com/), all from a context menu on the Go button (and on the toolbar button provided by Go Up, if you have that extension installed).
+ Download and Install Digger!