Auto Copy
Auto Copy is a Firefox Extension.
You can download it from the Firefox Add-Ons site.
With the Auto Copy extension, any text that you highlight on a webpage is automatically copied to your clipboard.
This extension saves you a couple of steps that you would normally take (i.e., right-clicking and choosing “Copy” from the Context Menu).
Just highlight some text (see below) and it automatically copies to the clipboard.

I have to admit, it may take awhile to get used to this extension, especially if you’re conditioned to right-click and copy. But once you get the hang of it, your productivity will increase.
Auto-Copy has an icon that sits on your status bar. When the extension is active, this is how the icon will appear:

To de-activate Auto Copy, just left-click on the status bar icon:

Here is a screenshot of the Auto-Copy options window:
















