I remember vaguely, about discussion bulletin boards (vs blogs?), but wanted to compile a list just as a matter of course.
vBulletin (http://www.vbulletin.com/)
vBulletin is a powerful, scalable and fully customizable forums package for your web site. It has been written using the Web’s quickest-growing scripting language; PHP, and is complimented with a highly efficient and ultra fast back-end database engine built using MySQL.
vBulletin is the ideal community solution for all medium-to-large sites.
Leased Option: $85
Licensed Option: $160
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phpBB (http://www.phpbb.com/)
phpBB is a high powered, fully scalable, and highly customizable Open Source bulletin board package. phpBB has a user-friendly interface, simple and straightforward administration panel, and helpful FAQ. Based on the powerful PHP server language and your choice of MySQL, MS-SQL, PostgreSQL or Access/ODBC database servers, phpBB is the ideal free community solution for all web sites.
Cost: Free (open source)
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These are the two that I am most familiar with and didn’t know if the bulletin board system was still in contention.
Best-
Lisa