How can I structure an ASP.NET project for re-use

Question

I am in the process of designing a web application which will have multiple installable modules that provide different functionality. There's a lot of common stuff going on here and I have 3 C# class libraries that I know will be easy to use on different projects.

The bit I am stuck on is the actual website itself. Ideally I'd like to make an ASP.NET page library that can be re-used over multiple projects but I understand that this is not possible.

How do you guys structure your website projects so that pages can be re-used across multiple projects? So far the only solution I've come up with is to create a repository in SVN and have it referenced in the svn:externals properties of the main project. This allows me to add pages to that directory that are common to all websites, and I know I will be able to use this to check them out to other projects. However, I feel this is a bit clunky and will cause problems when creating new projects (there'd be a number of steps to creating the new solution, ensuring that the right externals are in place).

Is there a better solution? What is the best way when you want to share common ASPX files across multiple client projects? How do you manage changes against them?

Thanks in advance!

EDIT:

Many thanks to David for his response. I've had more thought on this and thought I'd list some of my more concrete ideas/concerns. Firstly, a bit more about the project(s). Primarily, it's a CMS. However, we also have clients that will want CRM, and there's also clients that want neither and want an entire bespoke system from the ground up.

In my original post above, I spoke about having subdirectories of the main root (e.g, cms), using svn:externals to allow easy re-sharing of web pages across multiple projects. I am beginning to think this is the only way to do this. One thing that bothered me was if the client's url was:

http://www.shotgunanddribble.com/cms/content.aspx

However, I think I can use the Application_BeginRequest to mitigate horrible urls by rewriting them according to the configuration of the client's site. E.g, if a customer was just a CMS I could rewrite their Top-level-domain to /cms/. Same with if they were a CRM. If they were both:

http://www.shotgunanddribble.com/ -> /cms/

http://crm.shotgunanddribble.com/ -> /crm/

Is there any downside to using these kinds of rewrites? I think that, unless anyone else has any magical ideas, svn:externals is my only hope.

Answer 1

The actual code is easy enough to put in other assemblies and inherit from, but the ASPX files are definitely a different story. How about a common library of user controls to contain most of the display content, and each project would have its own pages which mostly just frame the user controls? I've never tried it, so there may be some "gotcha" that I'm just not picturing right now.