Archiseek: online magazine dedicated but not limited to Irish architecture.
Architecture_MPS : Architecture_Media_Politics_Society online journal.
Artifex Press. E-catalogues raisonnés of contemporary artists. Catalogues are free with registration for a limited time period.
Blue Mountain Project: "freely available digital repository of important, rare, and fragile texts...research collection of art, music, and literary periodicals ...1848-1923." (from Princeton)
Centre for Reformation and Renaissance Studies, Victoria University at the University of Toronto: Journals.
Experiments in Print: A Survey of Los Angeles Artists' Magazines from 1955 to 1986. (East of Borneo essay)
Guggenheim Museum Historical Catalogues. Freely accessible. Other Guggenheim essays also available here.
Ijele: Art eJournal of the African World. Online subscription journal of contemporary art and architecture, art history and criticism.
Journal of Historians of Netherlandish Art. Open access, refereed scholarly journal.
Public Domain Review: "a not for profit project dedicated to showcasing the most interesting and unusual out-of-copyright works available online." Lots about art, music, literature, history, etc.
Romantic Circles Praxis Series. "Devoted to using computer technologies to investigate critically the languages, cultures, histories, and theories of Romanticism.
Royal Academy of Art Winter Exhibition Catalogs 1870-1939.
Task: A Magazine for the Younger Generation in Architecture. Student journal published by architecture students in Cambridge, MA between 1941 and 1944. First issue published by students from Harvard, MIT and Smith College.
Tate Etc.: online journal of the Tate Gallery.
Wilson's Photographic Magazine on Google Books.