If you're using Firefox on all the machines, it looks like that functionality is now built in. It's called Firefox Sync.
Firefox Sync lets you take all your Firefox data (such as your bookmarks,
history, passwords, add-ons and open tabs) with you wherever you go.
You just set up Firefox Sync on your home computer and your Firefox data
will be securely stored on our servers and synchronized automatically from then
on. Then, when you set up Firefox Sync on your work computer (or even your
phone running Firefox), your Firefox data will be automatically synchronized
with your home computer.
Update: I do see that you're looking to sync specific bookmarks, not the whole lot of them. Firefox Sync doesn't appear to have that feature yet, but it still may be a viable option.
Update 2: If you were, say, in a work desktop, work laptop, home computer environment, and only wanted to sync the work links, you could sync all the bookmarks on the work machines. Then, if you needed a work bookmark at home, log into the web interface for it. It's not perfect, but it's something.