I never knew you could do this!
- In Firefox, click the Bookmarks menu and Organise Bookmarks…
- In the Bookmarks Manager, click the toolbar button with a star
- Click Export HTML… and choose a place to save the exported file
Now you have a tidy, one HTML file backup of all your Firefox bookmarks that you can even open and click links in, and reimport into another machine!
I've been a heavy Delicious user since 2003 (so was mum), but sometimes random links find their way into my Bookmarks toolbar. Not enough to warrant use of Mich Kapor's FoxMarks, but its good to know I can back them up :)