As much as I love cables, I've always been intimidated by them. If I follow the chart carefully, I can make them happen, but I've never understood exactly how it is that they work.
Cable Left, Cable Right: 94 Knitted Cables solves the mystery, explaining how he same exact four-stitch cable can be abbreviated eight different ways - no wonder I've been confused! The book contains a wide variety of cable charts, which explain how the cables do what they do. It also explains how to make them even more involved by using textured stitches within the cable, multiple colors, and beads. It also gives tips for designing with cables and how to work increases and decreases into the pattern.
I definitely want a copy of this book in my knitting reference library.