The URL Mapping functionality in ASP.NET 2.0 has one major shortcoming. It doesn't support Regular Expressions. So, I've made my own implementation of the URL Mapping functionality that supports Regular Expressions.

Link to Code: http://pietschsoft.com/Blog/archive/2005/11/12/762.aspx

Scott Guthrie mentions my code in one of his blog posts.
http://weblogs.asp.net/scottgu/archive/2005/11/14/430493.aspx