I'm not sure of how many ClickOnce user's there are out there but, as my last post suggests, I have been an avid user of the system for years now, in spite of it's short comings.
While working with the multiple applications that I manage, I have had times where it would have been convenient for me to be able to publish an application to a test location so that key users could test an update before it is published to the primary install point. This can be done, but you have to change a few application settings before publishing your test application. The changes are simple but can be prone to user error.
In response to this need, I've posted a Feature Request on the Microsoft Connect site for the ability to create a secondary or multiple install points for ClickOnce applications. If you would find such a feature useful, please follow the link and vote-up the feature.
MS Connect: Allow ClickOnce Applications to be Published to a Secondary, Test Location