Knitting has become cool. Reduce, Re-use, Recycle is the latest mantra. "Retro" is cool. Obviously, then, darning should become the latest cool "retro" skill.
Once you've put many hours of time and care into knitting a pair of socks, it doesn't make a lot of sense to throw them away because of one little hole. Here's how to darn it:
Thread a blunt needle with yarn that matches your sock yarn in colour and weight, if you want the patch to be inconspicuous. If you want to show off your skill, thread it with a contrasting colour. Put something round into your sock to hold it in shape while you darn: a lightbulb, or an orange, maybe.
Sew a series of parallel lines across the hole, making a few stitches in the good fabric adjacent, to "anchor" the yarn.
Now sew a series of lines perpendicular to the first set, weaving the yarn under and over in a basketweave pattern and again "anchoring" the yarn in the good fabric.
Your patch is done. Show it off.