From the National Science Foundation, the massive body of written work and correspondence Einstein left behind, the Einstein Papers Project, currently housed at the California Institute of Technology, is dedicated to collecting, editing, translating and publishing.
The Center for History of Physics, part of the American Institute of Physics, brings together information from Einstein's early years all the way through to his later life. It includes all his major works as well as essays from historians on the impact of his work.
This site comprises of fourteen digitized volumes containing the papers of Albert Einstein, in addition to correspondence. It also has related works and information on the partners who procured the digitized content.
This site contains modules that relate Einstein's theory of relativity along with animations. The links provided with the modules go into further depth about the ideas presented. The modules require Adobe Flash Player.
This site focuses on three items: 1) a manuscript in Einstein's own hand complete with editorial markups for page proofs as well as his prediction of the Bose-Einstein condensate; 2) typed manuscript with handwritten formula trying to find covariant equations for the gravitational field; and 3) a page proof of Einstein's "Propagation of Sound in Partly Dissociated Gases."
This feature, based on a traveling exhibit created for the Institute for the Advanced Study in commemoration of the Einstein centennial in 1979, discusses the general ideas addressed in each of the four major papers of 1905.