Why not spend the end of summer reading to improve your vocabulary?
Rather than selecting the same old subjects, branch out into a new topic area.
Or, spice up your media choices: try articles, blogs, books, essays, letters or speeches by your favorite authors or historical figures.
For new meaning delivered to your inbox, try an online "word-a-day" service through, for example,...
Science and technical writers especially might want to check out Trevor Quirk's article in Nature magazine (July 26, 2012, Volume 87) on the proper use of jargon.