I figure some here will be interested in this.
http://shared-app-vnc.sourceforge.net/
"The main advantage of SharedAppVnc over traditional VNC is its ability
to share individual windows rather than the entire desktop. Users
typically have some applications which should remain private, such as
email, and some applications they would like to share. Normal VNC is
only able to share a user's entire desktop and thus does not lend itself
well to a combination of shared and private data."
So, for example, you could share out just a couple of windows, and you
can even rearrange these on the client, differently to how they are
presented on the server. Could just share out a media player, for example.
No Windows client or server yet, but planned.