State of Digital (and in the past State of Search) from time to time organises special events on the site and gathers information on specific topics. Find an overview here.

Online-marketing-talks-sidebar Everthing you need to know about Google+  white-space
Everything you need to know around events Overview of events in 2013
State-of-Search-my-moment-2012 Google-Easter-Eggs
Infographics on State of Search