CheatKeys - View Windows keyboard shortcuts in the current application.
skribbl - Word guessing based on drawing.
TLDR pages - The TLDR pages are a community effort to simplify the beloved man pages with practical examples.
LetsDraw.It - Guess and Draw, Drawing Battle, Pictionary, Copy picture - online drawing games where you can compare your skill with others.
cheat.sh - The only cheat sheet you need Unified access to the best community driven documentation
gartic.io - Draw, guess, and win!