People often ask me which pop-gen book they should read to understand some of the content on this site.
Below are a list I've found useful.
An Introduction to Population Genetics Theory.
An old classic.
Heavy on theory and derivation.
Not relevant to modern concerns.
Population Genetics: A Concise Guide.
The subtitle says it all.
The gentlest book on the list.
An Introduction to Quantitative Genetics.
The Bible of population genetics' sister field.
Elements of Evolutionary Genetics.
An encyclopedic survey which is framed by population genetics.
An Introduction to Population Genetics: Theory and Applications.
Relatively unpolished, but with an emphasis in genomic methods and questions of relevant to researchers working today.