A pair of my wool socks just got a hole in it, and Yaty said it is way too tough to fix the hole, it's just easier to buy new socks. I remarked that there must be a guide to darning socks online, and while I agree that athletic socks aren't worth the time, my yummy REI wool socks just may be worth the trouble. Rants and Ramblings to the rescue with Just In Time How To advice:

Craftzine.com blog: Darn It!:

When you darn, you are essentially reweaving the textile; with modern knit items, it's a little bit trickier because you need a similar stretch as the base material, but still doable. The old adage "a stitch in time saves nine" is something everyone should pay more than lip service to: it's a lot easier to repair a small hole or threadbare fabric than a gaping vent! Repair your moth holes or tears right away and you'll thank yourself later.

Props to Rants and Ramblings.