WikiTribune - Evidence based journalism, from the founder of Wikipedia
Brain Games - Boost memory power with free brain games
Data Dashboard by Wikimedia Foundation - Compiled data of the Worlds busiest public site
Dualnback.works - Dual N-back is a specific brain training exercise, that's been shown by research - it might improve fluid intelligence.
Neighborhoods.nyc - Hyper-local alerts targeted by NYC neighborhood
Pixelogic - Daily Picross - Nonogram logic game with 5000+ puzzles and a daily puzzle