These are some books written by members of the meetup.

R for Everyone

Jared P. Lander

Bayesian Data Analysis

Andrew Gelman, John B. Carlin, Hal S. Stern, David B. Dunson, Aki Vehtari & Donald B. Rubin

Testing R Code

Richard Cotton

Analyzing the Analyzers

Harlan Harris, Sean Patrick Murphy & Marck Vaisman

Bad Data

Q. Ethan McCallum

Applied Predictive Modeling

Max Kuhn & Kjell Johnson

A Quantitative Tour of the Social Sciences

Andrew Gelman & Jeronimo Cortina

Machine Learning for Hackers

Drew Conway & John Myles White

Learning R

Richard Cotton

Testing R Code

Richard Cotton

Machine Learning for Email

Drew Conway & John Myles White

Text Mining with R

Julia Silge & David Robinson

Teaching Statistics: A Bag of Tricks

Andrew Gelman & Deborah Nolan

Doing Data Science

Cathy O'Neil and Rachel Schutt

Parallel R

Q. Ethan McCallum