Great article on Http Handlers and Modules
I'm still writing part 2 and 3 of the "Let's Extend ASP.NET" article. I'll really try to post at least part 2 until the end of the week but I can make no promises. In the meantime, if you want to look further, there's a MSDN article that shows a great implementation of Http Modules and Handlers to build an error logging mechanism. This is actually one of the common utilizations of Http Modules but they did a great job in this specific implementation allowing you to view the error log in a web interface or even as a rss feed. Cool!
http://msdn.microsoft.com/asp.net/default.aspx?pull=/library/en-us/dnaspp/html/elmah.asp
