"The SPARC Author Addendum is a legal instrument that modifies the publisher’s agreement and allows you to keep key rights to your articles. The Author Addendum is a free resource developed by SPARC in partnership with Creative Commons and Science Commons, established non-profit organizations that offer a range of copyright options for many different creative endeavors."
From the University of Nottingham, SHERPA/RoMEO can be used to find a summary of permissions that are normally given as part of each publisher's copyright transfer agreement.
What is open access? Nick Shockey and Jonathan Eisen take us through the world of open access publishing and explain just what it's all about. (via PHD Comics, Oct 25, 2012)