Let's say you have a mainframe that is running Xclients for Xservers located on people's desks. Let's say all of these people are logged in using the same username (don't ask) and that you'd like to instead store GConf settings based on the value of $DISPLAY. GConf would actually appear to let you do this, although it's through a non-obvious construct.

The file /etc/gconf/2/path contains a list of directories that contain GConf trees. It reads from top to bottom, taking the first match for a key, and obeying the access directives. If it's not obvious how it works, it's in the sysadmin guide.

You can edit the line that defines your ~/.gconf directory to something like:

xml:readwrite:$(HOME)/.gconf/$(ENV_DISPLAY)/

In fact, you could use any environment variable you wanted with that $(ENV_...) glob, as well as the more well known $(HOME) and $(USER). It's possibly the most useful and crackfilled feature I've come across today.

If you only want certain usernames to have this feature put the configuration in their ~/.gconf.path and make the file immutable.