Academic Search Complete - A good source for undergraduates; many full-text articles; interdisciplinary, with good coverage of the applied sciences.
Compendex + Inspec- indexes scholarly journals and conferences in all areas of engineering.
IEEE Xplore - Provides full-text access to IEEE and IEE journals, conference proceedings and current IEEE standards covering electrical and computer engineering, electronics, computer science and physics.
Annual Reviews Online - Provides full text access to all volumes published by Annual Reviews. Covers topics in biomedical, physical and social sciences.
CQ Researcher - Explores a single "hot" issue in the news in-depth each week. Every report is written by an experienced journalist and features comments from experts, lawmakers and citizens on all sides of every issue with numerous charts, graphs and sidebar articles. Example reports include: Plagiarism and Cheating; Genetically Modified Food; Synthetic Biology.