I have used alot of website software throughout the years I have been developing, some of which you can find listed below.
Content Management Systems (CMS)
SilverStripe
Official website: silverstripe.org
Example website: monkeyben.co.uk
Coding language: PHP
SilverStripe is my CMS of choice for freelance work. SilverStripe has an easy to use, fully accessible administation backend for managing website content and is fully capable of extending for any bespoke purposes.
TYPO3
Official website: typo3.org
Example website: nottinghamartstudio.co.uk
Coding language: PHP
This was the CMS that I used at the time I worked at my previous job. It is very powerful but has a steep learning curve.
Joomla
Official website: joomla.org
Example website: seerysgardenservices.co.uk
Coding language: PHP
I have only worked on one website, that I inherited from elsewhere, thats uses Joomla.
Metafocus Web Manager 1
Official website: metafocus.co.uk
Example website: panthers.co.uk
Coding language: ASP Classic
An inhouse CMS produced by Metafocus, which I have worked alot with. Soon to be replaced, but works well for small, one content managed area, websites.
DotNetNuke
Official website: dotnetnuke.com
Example website: aspetto.co.uk
Coding language: ASP .NET
A CMS with plenty of functionality and multiple content management area capability. Though I have not used it extensively, I found it to be relatively user friendly.