Wordpress is the "small" CMS which became famous as a bloggersystem since it´s first stable release in 2004.
Open Source Infos
Joomla ist the CMS, which once started as Mambo and is used by more than 3% of all websites all over the world.
J!Praxis is specialized on this favourite CMS since 2006 and is working nearly to 100% with it.