Useful tools for improving vocabulary
Academic Word Lists
Very useful academic word list. Combine it with the Adobe Advanced PDF search techniques in the Computer-assited writing section of this site to see how these words are used in your field.
Same list linked to the dictionary and a more specific list by field
Academic Vocabulary Wordlist with exercises
Commonly confused words http://www.wsu.edu:8080/~brians/errors/errors.html
American SAT question of the day
Word of the day for the SAT