In this post, I will list some useful open datasets.
CrowdFlower
CrowdFlower is a crowdsourcing platform. Thanks for them to support researches in crowdsourcing area. They open some completed datasets, called Data For Everyone processed on their platform for researchers in crowdsourcing area to test new methods.
AMiner
Aminer is a researcher mining platform, which ranks researchers in many areas based on their influences. Also the group developed Aminer is active and successful in data mining area and published many papers in KDD in recent years. They open their datasets used in their papers for other researchers to utilize.