GeekList: Free-to-print games that might actually be worth printing: "Fast, fun, and easy to make. The game simulates a WWI biplane dogfight. You play cards, trying to outmaneuver your opponent, hoping to take a shot at him when he's vulnerable. It plays quick and stores small -- perfect for a quick game inbetween other games.
Here's a little suggestion if you plan to make this one -- print the game twice on different colored card stock. Cut everything out and separate the Allies and German cards. You'll end up with two copies of the game this way, but it'll be a lot easier to sort them out if they get mixed. (look at the PDF file for this game and you'll see why I suggest this method.) "