If you are building a new ASP.NET application, SEO has become a big factor in how you plan the structure / code of the site.  But quite an important part of the site which are often overlooked are the URL’s, and a lot of people do the basics which I’ll show below but there are a few common things people tend to miss or never thought could be a problem. I use ISAPI rewrite for most of my sites, which is an amazingly effective tool for sorting duplicate content and SEO issues which I’ll show below

1.) Rewrite your URL’s to be useful / descriptive and stick away from using the old dynamic way

i.e. mypage.aspx?e=54&b=99

Google even tell you this is not ideal in the webmaster guidelines (See bottom of Design & Content Guidelines section) - http://www.google.co.uk/support/webmasters/bin/answer.py?answer=35769&hlrm=en_uk More...