WebGameList.com

http://www.miniclip.com/games/genre-13/action/en/

http://www.agame.com/games/action

http://www.ea.com/action

http://www.y8.com/tags/action

http://www.gamespot.com/genre/Action/pc/

http://armorgames.com/category/action

http://www.videogamer.com/top-games/pc-action-games-all-time/