I've just finished setting up a great extension for firefox.
Those of you that have more than one computer, or several users on the same machine, along with a set of bookmarks for each, will find it very useful.
Basically it requires you to have access to an ftp account in order to store your synchronised bookmarks. You then setup the extension on all of the firefox installs you wish to use it on, and let it do its stuff.
So, I set it up 4 times this evening - once on my server and 3 times on all 3 users on my laptop. I'll probably set it up a 5th time at work tomorrow. I then organised all of my bookmarks on my laptop, and then synchronised them. Each time I login to a different user, or different computer and open Firefox, the bookmarks are synchronised allowing me to take the same set from place to place. Perfect!
You can get Bookmark Sync and Sort here.