Historically, a tinderbox is a small container containing flint, steel, and dry, finely-divided fibrous matter (such as straw), used together to help kindle a fire. In conventional usage, the term "tinderbox" refers to something that is so dry that it could catch on fire with the slightest provocation, perhaps even spontaneously.
As applied to the web:
The Tinderbox.org is an interactive community for professionals involved in applying the latest social networking tools to media, customer or enterprise communities. This community's participants learn how to spark robust interaction online with the latest news, articles, forums, blogs and commentary from their peers. Currently in beta, The Tinderbox.org is rapidly evolving into the go-to source for all things related to web 2.0 technology applied to business vertical markets.
The underlying technology is provided by FireStarter (Media Edition) as a fully integrated platform that enables media companies to quickly deploy online vertical communities that connect market participants.