While using WordPress as a CMS in a project of mine, I had a problem with linking to other internal pages easily. There is no way in the wordpress link dialog right now to refer to an internal page. But just using the absolute URL is no real solution, since the pages or even the site base URL might change. There are nice solutions to this problem, like creating your own shortcode for that. (German) While that is a neat solution, it is not user friendly, which I need or at least want for my CMS thing. So I searched a bit more and found Absolute Links, a plugin that converts all internal links to the default format (/?page_id=6) and while rendering replacing that with the current setting for permalinks (/about/contact). On the outside everything looks great, you can input the links as you like, but you stay a 100% flexible. Simply a great plugin.