As I mentioned, my aunt had worn through the heel bottom of her favorite pair of socks. I got inspired yesterday to try fixing them: although the original socks were knit cuff-down, I figured I could fix them using the heel turn method from my toe-up Evil Genius Socks.
I ran a circular needle through the stitches along one side of the heel flap, across the bottom, then up the other side of the flap. I purled back across those stitches with my replacement yarn, and then followed the Evil Genius Lessons to turn a new heel and work a new flap.
I had to modify the instructions slightly, since I couldn't work the complete sock round to pick up up my wraps (I just left the wraps in place). I grafted the top of the new flap to the bottom of the old cuff, then cut and unraveled the old heel.
It's not perfect. Obviously, the pretty, pale blue sock now has a drab, gray flap stuck on the back of it. (Still, it coordinates better than all the other options I considered at the yarn shop). I'm sure it won't be as comfortable as before.
Both socks began to unravel in unexpected places once I was finished, so I had to do some emergency suturing to keep things together. I expect that there are other areas where the old yarn will work loose from the new heel.
Still, it was worth a try. I'm really rather proud to have figured this out, and amazed that it worked as well as it did. It's probably not permanent (and I hope my family doesn't expect me to make a habit of such repair jobs), but I think it will squeeze a little more life out of these socks.