I've compiled a very short list of a few of my most favorite MAC products! Although the brand can be pricey, here are some products that have multiple uses -- these products are definielty worth the money.
MAC Mineralize Skin Finish Natural

-Used to set foundation
-Buffed onto face in place of foundation for a light, matte coverage
-Used to blend out lid color
-Are you getting a little lighter in the winter months? Use MSF to contour cheekbones
MAC Melon pigment

-Used as a lid color (can be used wet or dry)
-Used to highlight cheekbones, this is especially flattering for WOC in place of vanilla pigment
-Used to liven up the lips by applying to the center of the lips after lipgloss
MAC 224 brush

-Used to blend out lid color
-Used to apply highlight to cheekbone & temple area
-Used to apply cream concealer under eyes
-Used to apply a light powder to set under eye concealer
MAC Greasepaint Sticks

-Used as a base to make eyeshadows pop
-To be used as an eyeshadow all over lid
-To be used as an eyeliner
Let me know what some of your most favorite, versatile products are!