I for one LOVE data and research, and there's been a glorious spate of new studies coming out recently with cold, hard facts on SEO best practices. I really enjoyed reading recent articles about the impact of Pigeon, recent research about Google's changing of title tags, and 7 Key Factors in On-Page Optimization because they were all well-supported by legitimate research. You don't have to read all of them - but you better know that your digital marketing agency is on top of these important trends!
Though not exactly SEO, this list of 750 subreddits is fantastic for link-building and generating buzz amongst specific tribes.
Here's to more research and data-collection in the SEO/online advertising industry. Thank you, big agencies, for taking the time and energy to do this research, because it really helps all of us in this growing industry.