Predatory publishers publish fake journals to exploit the open-access model in which the author pays. They set up websites that closely resemble those of legitimate online publishers, and publish low qualty journals.
Some predatory publishers spam researchers by soliciting their work and invoicing them only after publication.
Jeffrey Beall, a librarian at the University of Colorado Denver, keeps people informed about predatory publishers in his blog: Scholarly Open Access. This is a forum in which scientists can raise their concerns over the practice.
Jeffrey implores scholars to resist the temptation to publish quickly and easily. The research community needs to use scholarly social networks to identify and share information on publishers that deceive, lack transparency or otherwise fail to follow industry standards.