Software is free to use.

Support for both cookie and URI-based sessions

Unlimited forums, private forums, and search feature built in.

Polls can be added to messages.

Moderation features including word censoring, banning users by email address, username or single/multiple IP address or hostname.

Private messaging system and email notification of posts as options.

Webhosting adequate to handle the CPU requirements and your diskspace needs which depend on how popular your board is.

A SQL database system, one of:

• MySQL (3.22 or higher)
• PostgreSQL 7.0.3 or higher (preferably 7.1.x or 7.2.x)
• MS SQL Server (7 or 2000) directly or via ODBC
• MS Access (2000 or XP) via ODBC

PHP (3.0.9 and above or preferably a recent 4.x) with support for the database you intend to use above

Auctionbytes

Dragonscouts

Opinionator.net