These are some books written by members of the meetup.

Service-Oriented Design with Ruby and Rails

Paul Dix

Testing R Code

Richard Cotton

Data Science at the Command Line

Jeroen Janssens

R for Data Science: Import, Tidy, Transform, Visualize, and Model Data

Hadley Wickham

Forecasting: principles and practice

Rob Hyndman

Python for Data Analysis

Wes McKinney

Doing Data Science

Cathy O'Neil and Rachel Schutt

Bad Data

Q. Ethan McCallum

Bandit Algorithms for Website Optimization

John Myles White

Data Analysis with R - Second Edition: A comprehensive guide to manipulating, analyzing, and visualizing data in R

Tony Fischetti

A Computational Approach to Statistical Learning

Bryan Lewis and Michael Kane

R for Everyone

Jared P. Lander

Learning R: A Step-by-Step Function Guide to Data Analysis

Machine Learning for Email

Drew Conway & John Myles White

Parallel R

Analyzing the Analyzers

Harlan Harris, Sean Patrick Murphy & Marck Vaisman

R Cookbook: Proven Recipes for Data Analysis, Statistics, and Graphics

JD Long

Pandas for Everyone: Python Data Analysis

Daniel Y. Chen

ggplot2: Elegant Graphics for Data Analysis (Use R!)

Teaching Statistics: A Bag of Tricks

Andrew Gelman & Deborah Nolan

Data Analysis Using Regression and Multilevel/Hierarchical Models

Andrew Gelman & Jennifer Hill

Machine Learning for Hackers

Feature Engineering and Selection: A Practical Approach for Predictive Models

Max Kuhn

Text Mining with R

Julia Silge & David Robinson

Getting Started with D3

Mike Dewar

A Quantitative Tour of the Social Sciences

Andrew Gelman & Jeronimo Cortina

Deep Learning with R

JJ Allaire

R Packages: Organize, Test, Document, and Share Your Code

Hadley Wichkam

Advanced R: Second Edition

Learning R

Bayesian Data Analysis

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

Applied Predictive Modeling

Max Kuhn & Kjell Johnson

Introduction to Empirical Bayes: Examples from Baseball Statistics

David Robinson

Red State, Blue State, Rich State, Poor State

Andrew Gelman