Code Project has a 4-part series on creating a web page class library that can be implemented in your web application:
- BasePage, MenuPage and VerticalMenuPage - A set of common, reusable page classes for ASP.NET applications.
- BasePage (continued) - Detecting changes in data controls in ASP.NET web forms.
- EmailPage - An ASP.NET page class that has the ability to e-mail its rendered content.
- PageUtils - A utility class containing some useful features for ASP.NET applications.