Learn a new language *and* help translate the internet FOR FREE! It's limited in which languages you have access to at the moment, but it's the most awesome idea ever. Maybe this can someday be used to also help preserve languages from being lost. But for now, if you've ever wanted to learn Spanish, French, German, Portuguese or Italian while helping to uberly geekify the internet into one of these fine languages, check it out!
Something both dear to my heart and terrifying to think about, the loss of cultures, of languages, of ways of thinking that we can't even imagine sometimes, let alone grasp ourselves. Knowledge and understandings that we lack in our 'advanced' and 'civilized' society.