Microsoft has recently announced a machine learning competition platform. As part of the launch, one of the first competitions is the prediction of brain signals. It has $5000 in prizes, and submissions are accepted thru June 30, 2016.
Google and Tableau have teamed up to offer a big data visualization contest. The rules are fairly simple, just create an awesome visualization using at least the GDELT data set. Finalist will receive prizes worth over $5000 and even some will get tours of Tableau and Google facilities. The contest runs thru May 16, 2016.