I love me some Xmarks.
Formerly Foxmarks, Xmarks allows you synchronise my favourites/bookmarks across browsers and across machines.
If I’m at work and I bookmark an informative article on Safari, *hey presto!* I can find that same link already present on Firefox when I get home to finish up my reading.
Xmarks also allows you to configure ‘profiles.’ I can have a ‘work’ profile which excludes more personal links available in my ‘home’ profile. They have an online tool which is not too shabby either. I can see a preview of the page without launching another tab or window.
There’s a social bookmarking component to it, which I generally ignore, but you may find helpful.
Try it out at Xmarks.com!