I haven't actually done it, but I think I know how to do it in theory. I
would set up the system as a server (which installs a slightly different
version of Ubuntu, Set up SSH, FTP, FetchMail, etc and that should make
it ready. I'm sure there's hardening of the system to do to, but I'm
certainly no expert about that.

The server part (though I havent set it up for this purpose before) isnt
completely what I was thinking about. I think this person saw Google
Live Bookmarks or something and wants me to setup something like that.

Auto-authentication and login is my concern.

I've never looked into Live Bookmarks, so I can't speak to that.

As far as keeping all the data on a central server(s), we did that as
a rule at my place of employment.

We'd put everyone's home directories and all the shared data
directories on a central server (which usually shared disk space with
other servers on a SAN (Storage Area Network)), and then ran an nfs
server (software) on the server (the machine) and used the autofs
automount daemon running on all the clients to automatically mount the
home and data directories on any machine that the user sat down at. It
would mount a directory when it was needed, then time out and unmount
it after x minutes of inactivity.

The only real problem we ran into was file locking. It just wasn't too
useful or reliable over NFS and it bit us a few times over the years,
usually when a mail spool was being written to by a mail client and
the mail delivery agent at the same time.

I can probably remember how to set all this up under RedHat or a
clone, but I've never tried it in Ubuntu, I only started using Ubuntu
after leaving work, and I just don't need that sort of setup at home.

You are either looking at using a box as a server, OR you are looking
at creating a peer-to-peer network. Figure out which one, decide on
OS, and start your research from there. What you've given here has
too many options possible imho to give you a step-by-step. Best of
luck.

It's a lot of work, but what OS do you want to use. There are site out there
for WinBloz stuff to do that. In UNIX you would have to do a VPN for different
sites and maybe even VNC.