>Although I have built a decent class library I haven't used the form class much at all. I could never figure out a good way to get an icon/include file to all my forms. Now I wonder that if I take my form class, which is a subclass of the base class and subclass it again specific to my application will I be doing the right thing? This way I can use a common icon/include file among the app without while still having a common main subclass.

You can subclass your baseclass to make your own "framework" level class. That can be augmented with code that looks in a table and gets the name of an icon to display or just put in your icon name directly. Build all your new forms specifying that form as the basis, and they'll all have the icon and you can change em all in one place!