The best resource for current test materials for common graduate school and licensing exams is the Education and Career Center (Gale Presents Peterson's Test Prep). It includes study guides, practice tests, and other materials for the GRE, GMAT, LSAT, and other common tests. This database also has "Career Tools," including a Virtual Career Library and a resume builder.
You can also search in Primo Search to locate more print and electronic books in these areas. For example, try searching for the name of a test or use the general search term "examination study guides."