It's not that I think this is the best sock imaginable, but it's the best low profile sock I've ever found. The ample sticky silicone (I think) pad on the heel makes this sock do exactly what you're looking for. After years of wearing flats without socks, my feet are a lot happier now. And for me at least, the vamp on the toes is well below the shoe line on all my flats.

As other reviewers have mentioned, the size isn't on the amazon page. I ordered a large, sized for shoes 7-10 and it was just right for my size 8 feet. Maybe that makes all the difference, being toward the middle of the range.