Drupal is pretty good. Combine with the module 'htmlarea' to allow fancy mark-up iin the browser.
Wordpress has had good reviews lately. There's about about 1 million other open source cms's around. I've mentioned http://opensourcecms.com/ here before. You can try a few live from that site. Matt -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
