Very simple and very effective Rated 5 out of 5 stars

This add-on does a good job when you have a small number of tabs and you want to save them to multiple files. Moreover, it can be easily combined with the File Tile add-on (https://addons.mozilla.org/addon/file-title/) to save web pages using their title.

A possible improvement would be to save all tabs automatically to the Downloads folder, without asking for each file name individually, when the corresponding browser preference is set.