Affixing a gold star to a schoolchild's homework probably originated from the decorations in the military of gold and silver stars, which in the US is based on a complicated system representing various and multiple achievements. The adoption of the extra bonus of a gold or silver star for really making your teacher happy has, along with Scout badges, certainly contributed to the multitude of badges and achievements awarded in video games for devotion and other activities.
On E2, if you have enough GP to do so and are Level 1 or higher, you can award stars to other noders for whatever reason. This is found in the E2 Gift Shop under 'The Gift of Star': just enter the name and why in the fields. and the recipient will receive the message. Although gold may be the default, you are allowed to enter your own type of star, so you can choose silver, shooting, Hollywood, and even super!