If you've got:
Use an eyeliner in brown or espresso. Although I absolutely love black liner on blue eyes, the look can be too harsh for everyday wear. Try Bobbi Brown Eyeshadow in Espresso to line your eyes (using an angled brush like MAC 266), or her Creamy Eye Pencil in Dark Brown.
If you've got green eyes, consider yourself blessed. So many colors complement eyes of this color, everything from charcoal gray to brown. But my favorite color to enhance green eyes is a plum color. Jewel is known to be a huge fan of Prescriptives Softlining Pencil in Fig. Another great color to try is MAC Kohl Power Eye Pencil in Raven, a reddish black that looks amazing against green eyes.
Women with brown eyes can wear any color other than brown to bring attention to their eyes. Although brown liner is by no means forbidden for brown eyes, (I wear it myself nearly everyday for a natural makeup look) brown does very little to add "zing" to brown eyes. The key to making eyes "pop" is to line in a contrasting color, and my personal favorite color to line brown eyes is blue, especially navy blue. Take a look at Alicia Keys' eye makeup, the blue liner and shadow around her eyes is accentuating her brown eyes so much better than if she had stuck to a basic black or brown liner. Try duplicating the look using MAC Eye Kohl in Blooz, Elizabeth Arden Smokey Eyes Powder Pencil in Midnight, or NARS Eyeshadow in Night Flight. For a more subtle daytime look, try navy liner with a pearly rose eyeshadow on your lids: try Laura Mercier Shimmer Eye Shadow in Rose on the lids, and her Matte Eyeshadow in Twilight Grey in the crease for a great day-to-night eye look with navy liner.
Angelina pic via, Alicia Keys pic via, Jennifer Aniston photo via, Jewel photo via Yahoo! photos