Getting seo friendly URL’s depends on the CMS you are using.
Firstly, mod-rewrite is used in a .htaccess file to rewrite the urls based on certain patterns. Mod-rewrite is an Apache module that will take the url that is entered in your browser and make sure that the page at the unfriendly URL location is displayed.
Secondly, in some instances, the links in your actual CMS need to be changed to make sure they match the patterns you have specified in your .htaccess file.
This technique is often referred to as a Googletap for some reason. Another term used is “Permalink”. So if you are using PHPNuke, you can do a search for PHPNuke + Googletap or PHPNuke + Permalink and you should find info on how to modify your CMS.
The following is a snippet from my .htaccess file that rewrites some of my WordPress URL’s.
RewriteRule ^category/(.+)/page/?([0-9]{1,})/?$ /index.php?category_name=$1&paged=$2 [QSA,L]
RewriteRule ^category/(.+)/?$ /index.php?category_name=$1 [QSA,L]
Here is a link for a vBulletin Googletap:
xhttp://www.vbulletin.org/forum/showthread.php?t=91324