<p><a href="http://www.dictionary.com%5B/url%5D">www.dictionary.com</a> has a word of the day free service. though i find that these types of email services tend to build up in my mailbox...unopened...
i also spotted once that <a href="http://www.princetonreview.com%5B/url%5D">www.princetonreview.com</a> or something has word of the day email things too...</p>