MAC's Fluidline is one of the best makeup discoveries I've ever made. For years, I've been painstakingly sharpening my eyeliner to get that tiny point at the tip so that I could draw the perfect wingtips at the edge of my eyelid, as well as line my lower lid. My efforts were fruitless because the eyeliner would smudge and run throughout the day (and I've tried many different eyeliner pencils!), resulting in raccoon eyes, so I would have to reapply several times a day.
The day I got out of purgatory was the day I paid a visit to a MAC store and whined about my raccoon eyes. My makeup artist said, "I know just the thing for you", grabbed a magical little jar of Fluidline in Blacktrack (their darkest black) and an angled brush and went to work. A minute later, my eyes were in wing-tipped, cat-eyed heaven. I looked in the mirror, rubbed the Fluidline that was applied to my lids a little, and it didn't smudge. SOLD. I've been worshipping Fluidline since.
What I love about Fluidline is how easy it is to apply, and how just a minimal amount of it is necessary to make a dramatic effect. It's like a little pot of paint that you can paint onto your face with an angled brush, and this paint dries pretty much instantaneously and doesn't smudge afterwards. The icing on the cake is that it's available in a wide array of colors. I've also used Fluidline to draw moles for a bit of that Marilyn Monroe glamour, and to draw kitty noses and whiskers when I'm wearing my kitty ears. Again -- It's SMUDGE-PROOF.