I'm getting ready for an exciting project (more details later). The person I'm knitting it for wants yarn that's already in my stash, I'm just not sure if I'll have enough. While I wait for her to let me know length, width, etc., I needed to find out how many yards I actually do have on hand.
My desk drawers are mostly opened with knobs, two of which are spaced exactly two feet apart, so I used those to measure out the yarn on the slightly used skeins. Since the knob is at the end of a skinny post, I wrapped a spare shoelace around each until the post was about the same width as the knob so I could wrap the yarn around them and be able to pull it right off when done.
I wrapped the yarn around the knobs 50 times, tied it off into a hank (without actually cutting the yarn, of course), and repeated until done. Then it was just a matter of some simple math to figure out the total yardage: # wraps * 4 ft per wrap / 3 ft in a yd. [I used this same method to figure out how much yarn I need by measuring, then ripping out a swatch and counting the yards used. It ended up being 1 yd per sq. in. of knit fabric--how convenient is that?]
From there, I took the hanks and wound them into balls ...with an empty roll of toliet paper nostepinde! I followed the instructions at http://www.hatchtown.com/nostdir.html. I'm quite pleased with the results; even the first one looks much better than any other ball I've wound: