In The Hobbit, the sword Sting glows blue whenever Bilbo Baggins approaches orcs or goblins--a convenient feature in Middle-earth. In the real world, free wireless detection is more useful. "We're always looking for fun projects that get people excited about DIY culture," says Zach Supalla, whose company, Spark IO, produces hardware for making Internet-connected devices. So Supalla and his co-workers used the Spark Core, their Wi-Fi development kit, to hack a light-up toy Sting. Now it glows in the presence of unsecured Wi-Fi networks, not enemies.