The non nasty way to do this, is to have a class derived from Page, which returns a strongly typed version of your master page derived class, instead of just the base master. Then you can access the proprties of the master page neatly in any page derived from your new base class. A new base class lets you define all sorts of things and make them visible to all pages, as well as putting any code to check if a user is logged in, in one place.
Christian Graus Driven to the arms of OSX by Vista. Read my blog to find out how I've worked around bugs in Microsoft tools and frameworks.