Shared Bookmarks, do they exist?

I’m after a system where by users of my community computer labs can enjoy a new entry in their bookmark bar of items which are of particular interest and use.

Our system we use requires each user to have their own username and password and thus their own firefox profile, so we can’t do what the windows 7 labs would do which is just to add the bookmarks to the Internet Explorer session as the ‘User’ user.

So I had a look at social bookmarking services like delicious, but none of them provide a way to specify bookmarks or tags (which work) in a way that allows bookmarks to be populated.

I also looked for some scripts that perhaps might be able to open the firefox profile bookmarks html and edit it and sync one particular part of it up with a master file. But I haven’t been able to find such a thing.

So I turn to you dear reader; do you know of anything like this? Please comment below.