Drum Roll Please: Interweave now has a downloadable (PDF) sock spinning book available, called, appropriately enough,
Spin Your Socks.
In addition to excellent advice on spinning yarns specifically for sock knitting (which applies across the board, as far as I am concerned- ALL yarn is sock yarn), there are 8 sock patterns from back issues of Spin-Off magazine, including my own Spindle Spun Christmas Stocking.
It's a gorgeous book, downloadable (about 8mg), and eminently affordable. I am very proud to be a part of this lovely book. Check it out.