I'm just thinking out a loud here...
I just came back from SxSW in Austin. If you don't know about it, it's a massive Music, Film, and Interactive Festival and Conference. One thing I did while there was attend a session on Location Based Gaming. I wanted to learn and get more ideas for the 'Vocabulary Wars' project I have been kicking around.
I discovered a very neat geo game calledhttp://www.Dokobots.com - anybody here heard of it?
It's giving me ideas to go beyond the Foursquare notion of checkins and mayorships where players battle for geographic space and consider treasuring hunting as an aspect of Vocabulary Wars. Specifically, perhaps it would be fun for players to seek out virtual quizzes in the real-world environment and somehow have the quiz work with what's around them.
I'm going to digest this for awhile and think about an over-all story line that the Vocabulary Wars can work under.