A member of "The Brights" is one who identifies themselves as "a Bright." "Bright" in this sense is a new noun: a label of self-identification coined in 2003 meaning, "a person whose worldview is free of supernatural and mystical elements," and intended to encompass naturalists, atheists, agnostics, freethinkers, igtheists, and anyone else who can honestly affirm lack of belief in the supernatural. The purpose of the term is not to replace any existing philosophical terms or the existing senses of the adjective "bright," but to provide a positive "umbrella term" that diverse people whose main shared characteristic is lack of supernatural belief can rally to for the purposes of political visibility and unity.
People such as Daniel Dennett, Richard Dawkins (originator of the term meme,) and James Randi have publicly come out as Brights. The idea was first advanced by freelance writers Paul Geisert and Mynga Futrell.
http://www.the-brights.net is the epicenter of the movement.
A log of web sightings (both supporting and criticizing the idea) can be found at: http://www.dangerousgames.com/~ironwolf/philosophy/bright-idea.html (Yes, this is a shameless plug.)