One of the most iconic makeup products is also one of my favorite components to my daily beauty routine: the MAC Paint Pot. The product can be used either for pigment, or for priming the eyelids before application of eyeshadow; I use it most often for the second instance, and it works wonders. I have mine in Painterly, a creamy nude beige color, but they are also available in a wide variety of other colors, both pearly and matte.
The paint pot intensifies the color of your shadows, making them vibrant and true. Green is really green; blue is really blue.