Last night I was working on an ASP.NET project in which I wanted to share a common UI between two different ASP.NET applications. I had created user controls that contained the UI elements, and I wasn't sure how to share these controls between applications, so I did some searching. I finally stumbled across this article on Microsoft's support Web site: HOW TO: Share ASP.NET Pages and User Controls Between Applications by Using Visual C# .NET. Following these steps allowed me to share the user controls between multiple applications without too much effort. In short, the steps are:
1) Add the folder containing the user controls to the Web server.
2) Create the virtual directory for the application in IIS.
3) Right-click the virtual directory, and create a new virtual directory for the user controls that points to the folder containing the user controls. (Note that the virtual directory for the user controls should NOT be configured as an application in IIS. You should click Remove if an application has been created for the user controls virtual directory.)
You should then be able to build and run your ASP.NET application using the user controls.