These are some books written by members of the meetup.
Hadley Wickham
Mike Dewar
Andrew Gelman, John B. Carlin, Hal S. Stern, David B. Dunson, Aki Vehtari & Donald B. Rubin
John Myles White
Bryan Lewis and Michael Kane
Rob Hyndman
Julia Silge & David Robinson
Tony Fischetti
Q. Ethan McCallum
Andrew Gelman & Deborah Nolan
Max Kuhn
JJ Allaire
David Robinson
Paul Dix
Richard Cotton
Harlan Harris, Sean Patrick Murphy & Marck Vaisman
Max Kuhn & Kjell Johnson
Hadley Wichkam
Jared P. Lander
Andrew Gelman & Jeronimo Cortina
Cathy O'Neil & Rachel Schutt
Andrew Gelman
Jeroen Janssens
Drew Conway & John Myles White
Chris Fregly & Antje Barth
Wes McKinney
JD Long
Daniel Y. Chen
Andrew Gelman & Jennifer Hill