Cool Math Games is a fun website. You can play games in school when your teacher isn't looking. It has games like Fireboy and Watergirl, which is a puzzle game. It also has Run, something like Flappy Bird on drugs.
Reddit is a great place for everything. People post pictures, or upload posts. There are many communities here, such as for gaming, art or anything else! The best thing is that it can be for everyone. Almost everything is user controlled.