These days, I know how to knit socks and I've managed to build up quite a library of sock knitting books. But whenever I see that the library has a new one, it has to come home with me. That's how I stumbled across Sock Knitting Master Class: Innovative Techniques + Patterns from Top Designers.
I'll absolutely be buying a copy of this one. It's got everything -- charts for different measurements and yarn requirements, explanations of how to knit socks on four or five dpns and different types of circulars, more toe and heel styles than I knew existed, different cast-ons and bind-offs for toe-up and cuff-down socks...
And the patterns! There are some gorgeous sock designs in this book. I buy fewer knitting books these days because between the free patterns I've queued on Ravelry and the books I already know, there are hundreds of pairs of socks I want to knit, but I could justify this book just as a reference for heels and toes.
I haven't looked at the included DVD, since I'd rather read about knitting than watch it explained.