One of the really powerful things we did in ASP.NET 2.0 was to build a pluggable provider abstraction for a web app’s file activity, and to then re-plumb the ASP.NET parser, compiler, and other path/content/page related work to go through it. What this ends up delivering is a lot of extensibility capabilities not possible in ASP.NET V1.1.
Some examples of what you could do:
1) Re-plumb the storage of a web-site from being the file-system to instead have all content stored in a database or some other store (btw -- the next version of SharePoint is using this mechanism to-do this).
2) Hook and modify path information, and plug into the compilation process of the web-site.
3) Perform richer validation analysis on content being parsed (for example: disallowing certain controls from being used if you want to lock down and only allow “safe” controls on a site).
Definitely a great blog to keep an eye on!