Vocabulary.com is an excellent vocabulary study service offering thousands of vocabulary practice lists and activities for students in elementary school through graduate school. In addition to lists of SAT, GRE, and other test prep words, you can find vocabulary lists that are attached to novels, historical documents, famous speeches, and current news articles.
When you sign up for Vocabulary.com you will be given an assessment quiz in order to give you suggested lists with which to start your practice. After completing the assessment you can use the practice lists suggested by Vocabulary.com or choose your own lists from the huge gallery of vocabulary lists.