phpBB: "Since its creation in 2000, phpBB™ has become the most widely used Open Source forum solution."
Informe.com, a free forum hosting site: "On the first day of 2007 we present you our free forum hosting service, Informe.com. Our project is powered by world's most popular forum engine, PhpBB, and we are not only providing you with the best PhpBB forum hosting service available, but also enhance the platform with ourself-developed mods available only on informe."
Karen Harker, on the web4lib list, gave an excellent summary of the appropriate uses of wikis, blogs and forums, which I am quoting here:
Since we have implemented both blogs and wikis for Library staff use, we have run into this problem often. These tools are quite different regarding communication modes and therefore do not work well for all roles. Here's a brief list that I use to decide on which tool to use:
-- Synchronous communication: Chat or VoIP
-- Near-synchronous: Email
-- Asynchronous and topical: Discussion forum
-- Asynchronous and primarily, but not solely, one-way: Blogs
-- Asynchronous and solely one-way: Private blogs
-- Collaborative Web site but not necessarily for communication: wikis
Blogs are not real good for true discussions...Discussion Forums (remember online bulletin boards) are much better at that. Blogs are good for regularly posting announcement-type info (alerts, links, funny stories, assignments, etc.), while allowing others to comment. This could be useful for "peer-reviews" of assignments, particularly related to creative writing or critical thinking.