Check out Barebones CMS without having to download and install it.
There are some differences between the live demo and the downloadable product. The live demo site is restricted to Designer and Content editor account types, automatically resets a session after 30 minutes, may occasionally run the latest beta version of Barebones CMS (usually only during a release cycle), has all demo Barebones CMS extensions installed (a subset of all of the available extensions), and runs isolated from the main web server environment.
Report problems with the demo on the forums.
Head on over to Download Barebones CMS and start developing your website.