Crosswords Arena - Word game, multiplayer and computer players
skribbl - Word guessing based on drawing.
Tanglet - Tanglet is a single player word finding game based on Boggle.
LetsDraw.It - Guess and Draw, Drawing Battle, Pictionary, Copy picture - online drawing games where you can compare your skill with others.
Quackle - Open-source word game similar to Scrabble. Features a board editor, analysis tools, and artificial intelligence that rivals the best players in the world!
gartic.io - Draw, guess, and win!