As cool as some of the new features in ASP.Net are, there are some simple interfaces that can open a door to a boatload of functionality for your web applications. I am talking specifically about the IHttpModule and IHttpHandler interfaces. Lots of developers are aware of the interesting problems that you can solve (cleanly) by taking advantage of these interfaces. Lots, however, are still in the mindset that to add new pieces of functionality that an .aspx / .ascx file has to be involved in the picture somewhere. This is just not the case. I am not going to rehash information that is already out there for consumption. Instead I will direct you to the site of James Kovacs, who has just published a great writeup on using an IHttpModule implementation for dealing with Site Availability issues.
If you are not familiar with these interfaces, read the article (along with his article on the ImpostorHttpModule), and start thinking of ways you can use these interfaces in your application. Some examples that I have used in the past are:
Just think of the things you could do!!