GVRL - "Gale Virtual Reference Library" - contains encyclopedias and specialized reference sources for multidisciplinary research, for example "American Eras" or "American Decades".
PLS (Peninsula Library Collection) ebooks are searchable through the PLS book catalog. NOTE: The PLS' multiple ebook databases require setting separate passwords etc. - see http://www.plsinfo.org/ebooks
HathiTrust is a reliable and increasingly comprehensive digital archive of library materials converted from print that is co-owned and managed by a number of academic institutions. Volumes that are considered in public domain (e.g. published in the US prior to 1923 or published outside the US before 1875, or government documents) are available full text.