The Impatient Woman's Guide to Getting Pregnant by Jean M Twenge

An easy read containing lots humour and explains how the body works.
Includes info on cervical mucus, temperatures and different ovulation predictors.
Meta-analyses of various different research papers, including the chances of falling (and staying) pregnant.
An interesting look on gender selection, what works (pre-implantation stuff), what doesn't (Gender Calendars) and what is completely wrong (Shettles).