A blog-less colleage of mine, Bryce, just discovered redirects in IIS 6, which is something new for me also.  Bloody useful if you are moving site content around, moving servers or just want to make URL's more friendly.

http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/41c238b2-1188-488f-bf2d-464383b1bb08.mspx?mfr=true

This is particularly relevant for sites with really long and complex URL's, e.g.: SharePoint, in which case you should also read:  http://www.toddklindt.com/blog/Lists/Posts/Post.aspx?ID=48