Multidisciplinary:
Sparknotes: http://www.sparknotes.com/biography/
DOAJ (Directory of Open Access Journals): http://www.doaj.org/
Google Scholar: http://scholar.google.ca/
BASE: http://www.base-search.net/Search/Advanced
INTUTE (academic website compiler): http://www.intute.ac.uk/

Science & Information Technology
PubMed: http://www.ncbi.nlm.nih.gov/pubmed
AGRIS: http://agris.fao.org/agris-search/index.do
(Food & Agriculture Organization of the UN)
ChemxSeer: http://chemxseer.ist.psu.edu/
SciTech: http://www.osti.gov/scitech/
POPLINE (Reproductive Health): http://www.popline.org/

Math & Economics
Econbiz: http://www.econbiz.de/
Gapminder (Statistics): http://www.gapminder.org
Sparknotes Econ: http://www.sparknotes.com/math/
Sparknotes Math: http://www.sparknotes.com/math/

Social Science:
EHPS (European History): http://primary-sources.eui.eu/tag-search
Archives Hub (Women’s History/Studies): http://archiveshub.ac.uk/features/genesis/
Worldometers (live updated stats): http://www.worldometers.info/

English
Sparknotes Liturature: http://www.sparknotes.com/sparknotes/
Sparknotes Shakepeare: http://nfs.sparknotes.com/
Free kids books (English & Spanish): http://www.childrenslibrary.org/icdl/SimpleSearchCategory?ilang=English

For Teachers
Lesson Planet: http://www.lessonplanet.com/
Lesson Plans: http://www.lessonplans.ws/
Classroom-Aid: http://classroom-aid.com/about/ 
Handouts & Activities: http://www.education.com
TLSBOOKS (K-6): http://tlsbooks.com/
Free Printables for Teachers: http://www.resources-teachers.com/
Free Math Worksheets: http://www.math-worksheet.org/
Math Teaching: http://www.mathteaching.net/