Trendio is a stock market for news trends – sign up and get $10,000 in fake money to trade on words. Trendio monitors their usage from various news sources, and the price increases or decreases based on how often the word appears in those sources. There is also a French version of the site, here.
This reminds me of Alexadex, a site that allows people to trade on any domain name that is tracked by Alexa. I had some fun with Alexadex a couple of months ago and it is still getting some buzz from bloggers.