PsycINFO is the best database for psychology research. It indexes and provides abstracts for the professional and academic literature in psychology and related disciplines (psychiatry, education, linguistics, neurosciences, etc.) and is produced by the American Psychological Association.
Sciences
Web of Science is a multidisciplinary database that indexes major journals in the sciences and social sciences, and is especially useful to find who cited an article after it was published.
Multidisciplinary Databases
Social Sciences Premium Collection is a core resource for research in the social sciences. Provides citations, abstracts, and full-text, along with dissertations, books and book chapters, and association papers.
Academic Search Premier is a good interdisciplinary database of citations, abstracts, and full-text of scholarly journals, magazines, and newspapers.