I have several friends who have had their eyeliner and eyebrows permanently done.
From what I understand, the eyebrows are done by first mapping out the shape of the brow. The brows are then shaved and they tattoo on the brows using small wispy strokes to get a more "hairlike" effect. (As opposed to drawing a solid line.) Then after a couple weeks, the eyebrows start to grow back in and *VOILA* darker, fuller-looking brows!
With the eyeliner, one friend originally did it in gray, but it faded. She then re-did it in a dark brown (she's fair complected) and in a fairly thin line across the lashes. It looks really good and very natural. Another person had the black eyeliner done. Hers was much heavier and it didn't look as natural. (She was fair too.)
Has anyone ever had their eyelashes tinted? Works wonders! I did a lot of it when I was doing hair. There is a special tint made just for eyelashes. (Regular hair dye is a MAJOR NO NO!) My neice is a tow-head and has white eyelashes to match. I tint her eyelashes for her and the difference it makes is pretty incredible (You can get the tint really close to the root of the lash, you can't get that with mascara). I do my own about every 6 months or so, plus, I can still wear mascara over it too!