Simple CMS or CMS that can manage multiple websites

Just a few links that I have found searching for a content management system - CMS that is simple, easy to mantain and would hopefully also give an option to manage multiple websites on multiple domains from one admin panel. The number of niche websites that I own is growing and I need an efficient way to keep an eye on them. Since sites are really simple I also need a CMS that is simple and lightweight.

I'm not sure if these links are the answer, just some bookmarks for me to research later on...

http://www.cmsmadesimple.org

http://www.razorcms.co.uk/

http://globalmoxie.com/projects/bigmedium/index.shtml

If you have any more, I am all ears!