If you do SEO your probably aware of what a mod_rewrite is.
Essentially it changes the URL of a link like this
http://darksat.x47.net/index.php?topic=460.0into something like this.
http://darksat.x47.net/topic/460.0.htmlor something more advanced with keywords and topic titles in the url like
yoursite.com/mod-rewrite.php
Mod_rewrite is designed for the apache server which is the most popular web server on the internet, but for people who are stuck with Microsoft IIS Server there is some handy software called ISAPI_Rewrite which will do the same job.
Unfortunatly its not free and not as fast or good as mod_rewrite but its great if your running a microsoft IIS server.
Check it out here.
http://www.isapirewrite.com/