Road to Revolution Game PBS LIBERTY!
This cool little game lets you ride from Boston to Washington by answering questions about the Revolution. Its a combination of basic facts and some interesting trivia - like Benedict Arnold's leg - which makes the game more fun.

Yet it would be better still if you got more points for actually going and reading the For More Info links in each answer. Indeed, here's a perfect call for open-sourcing a learning app. A great base, with sound subject and content. So much more could be built on it:

Narrate the questions.

More graphics.

Integrate the News accounts into the game.

Intensify the reward structure to keep players hooked.
So, PBS/TCPT, what about it? Emulate BBC; Creative Commons / open source your content?