Turn on Friendly URL

In the file /config/UrlRewriting.config one can place rules for rewriting URLs. Just add a rule like this.

virtualUrl="^~/blog/tag/(.*).aspx"
rewriteUrlParameter="ExcludeFromClientQueryString"
destinationUrl="~/blog.aspx?filterBy=$1"
ignoreCase="true"
/>


Refer to this post for more info.