Wordsmith is the best. They send you a new word in the email everyday. This is one of those things that would have been really big among many of us preparing for either the GRE or management entrance exams. Of course, back in the day, email was a weekly affair since paying Rs.25 an hour for just checking email or surfing while at the hostel seemed a bit much. Our source of difficult words was the Times of India editorial.
However, I subscribed to 'A Word A Day' recently because I thought it'd be interesting. It's been fun mostly, and you learn new things on the list all the time.
There are additional meanings to words though, that Wordsmith will not elaborate. Roshambo is probably one of these words. For a full treatise on this French word, read this.
For the pop-culture summary (much more interesting), read this.
As for the 'inviting' title, no thanks. I'd rather watch.