I'm a serious bookmark user myself, across several computers at once, both Linux and Windows (and maybe a Mac some day in the future.) I keep my bookmarks synchronized across all my computers with the Firefox Add-on Foxmarks. I heartily endorse Foxmarks for synchronizing Firefox bookmarks across multiple computers.
My other two most essential Firefox Add-ons, on a list of about 15 of them on this computer right now are:
The thing that bothers me about any kind of service that keeps a copy of your bookmarks remotely is privacy.
Say Obamaniacs want to single out pro-lifers for harassment. My bookmarks would be a happy hunting ground. Speaking of hunting grounds, they’d find a few pro-gun sites in my bookmarks as well.
Maybe the remote backup is optional with Foxmarks; I don’t know.
Sounds like that would be helpful between college and home . . . though I don’t know that I want the college aware of ALL my Conservative bookmarks! Sigh.