There is a TopCoder contest running right now that involves machine learning, crowdsourced data, and natural language processing.  There is $41,000 up for grabs!  It will be distributed in many smaller prizes so there are plenty of opportunities to win something.

You need to register by tomorrow (March 4, 2015) to participate!  

More details here:
https://www.topcoder.com/blog/registration-for-banner-is-now-open/