StarForums Free discussion board hosting with many categories to choose from. Paid version available. Ad-supported. http://on.starblvd.net/meet/

BoardHost Remotely hosted discussion boards. Free trial available. http://www.boardhost.com/

Network54 Board hosting service which features custom headers, footers, fonts and also password protected areas. http://www.network54.com/

VoyForums Free hosted discussion board service. Different layouts to choose from. Ad-supported. http://www.voy.com/

EzBoard Offers free and paid discussion board hosting. The free version is ad-supported. http://www.ezboard.com/

Board Nation Offers YaBBSE, phpBB and Invision Board forums. Free and paid services available. http://www.boardnation.com/

Homepagetools UltraBoard Provides free discussion boards based on Ultraboard. Ad-supported. http://www.homepagetools.com/ultraboard/

ProBoards.com Free remotely hosted message boards. Features sub domains and customizable layout options. Ad-supported. http://www.proboards.com/

Boards2Go Offers a free message board. This service is popup-ad supported. http://www.boards2go.com/

Bulletin Boards Offers commercial bulletin boards. http://www.bulletinboards.com/

Eboards4all Offers free ad-supported discussion boards. Features include customizable layout, smilies and moderator options. http://www.eboards4all.com/

ForumCo Multithreaded, unlimited categories and forums, moderators. Free. http://www.forumco.com/

Quick Topic Free web bulletin board which supports posting by email. Paid pro version available. http://www.quicktopic.com/

Delphi Forums Offers free and paid forum hosting. The paid offer is ad-free. http://www.delphiforums.com/

Hostboard Offers paid Ultimate Bulletin Board discussion boards. http://www.hostboard.com/

Lithium Technologies Commercial discussion board hosting. Features extensive management tools, to allow simple, easy management of communities with minimal moderator intervention. http://www.lithium.com/

myCool Networks Free Blazeboard hosting service with many categories to choose from. Ad-supported. http://www.mycool.com/

BoardServer Provides completely customizable message boards. Commercial. http://boardserver.superstats.com/

Fast Boards Offers free message boards. Custom layouts are supported. http://www.fastboards.com/

SiteForums Forums are easy to manage, flexible, and can be graphically customized. http://www.timtyler.com/siteForums/