We've gathered sentiments shared by our colleagues around the internet for you here, and encourage you to share your thoughts in the comments section below, about the man that helped move role-playing into the limelight of gaming.
Ars Technica: "Get out your classic rule books. Invite some friends over. Keep a chair empty for a fallen friend, and play for a few hours. Not online, in person. Order a pizza ... Remember Dave Arneson, a man who wasn't satisfied with the game when his parents brought home an Avalon Hill title. When he began changing the rules, he began changing the world."