I came across this a couple of weeks ago while doing some online sock yarn research: a post called Guide to Picking a Sock Gauge
in the blog section of the Suzi's Knits
site. While I'd already figured out on my own that the standard 8 stitches per inch listed in most sock patterns is downright wrong for many sockweight yarns (which is why I now habitually knit a larger size on smaller needles at a tighter gauge ... loose, floppy fabric = socks that fall down/wear out fast), this Guide is the information I really wish I'd had back when I first ventured into sock knitting. The post is from 2007 so it doesn't include newer yarns, but there's more than enough information to help you figure out where the skein in your hand fits in.
Also, if you scroll up to the top of the screen, there's another post where Suzi lists the qualities she looks for in a sock yarn.
P.S. I can contribute info on one of my favourite post-2007 sock yarns ... Crazy Zauberball
should be knitted at at least 9-9.5 stitches to the inch to produce decent sock fabric.