I know a lot of coders who love the System.IO.Path class. For those that don’t know about it, the class has lots of handy functions for dealing with paths from combining them to getting folder or file names from them. All these coders used to hate it when it came to web programming or any work with urls where they were unable to use the path class as thery had to deal with web addresses or "virtual paths".
The good news is that .Net 2 has the System.Web.VirtualPathUtility class which aims to be just and useful to web site developers as the Path class is to winforms and service developers. It has handy functions for getting relative paths from one virtual path to another or making them app relative etc.
Definitely worthing checking out if you are wrtiting code to handle re-directs or resource urls etc.