The URL Lister add-on for Firefox gives you the ability to grab all the open tabs you have, and collect them as a series of links, formatted in three different formats, so that they can be copied easily.
To use, all you need to do is right-click on one of the tabs, and select URL Lister. Next, you will see a box (like the one above) that will give you URLs (one per line) for each tab you have open. This makes it super easy to copy and save the links for later. You also have the choice to save the list as plain text URLs, a HTML coded list (for use in a web page), or a Linked List, which would give you the list of links with both HTML code around them an the traditional “list” HTML tags too.
This extension will also open a number of links. So if you have a list of links you need to open in bulk, paste them into the text box, and hit the “OK” button. After doing so, you should have each URL open up in its own tab.
You can grab the URL Lister add-on at the Firefox Add-ons site or learn more about it at the author’s official site. If you love lists and links, you will love this browser link lister.
Here is a tip I randomly ran across via Smart Productivity. Want to quickly copy and paste a text-based list of your bookmarks? All you need to do is right-click a folder icon in your bookmarks and select Copy. After doing so, you can right-click and select Paste to paste the list anywhere you need it. It will be saved to your clipboard, organized by folder names.
If you are looking for an extension to copy all the URLs in the open tabs you have in Firefox, there is only one choice you have. 
I like the PDF format and so do a heck of a lot of other people. It is as close to an “alternative standard” as you can get. It might not be used for everything, but what it is used for – it is used well. How would you like to be able to convert to PDF right from Firefox?