John Langford <jl@hunch.net>
... and many others.  The git log includes at least:

 Alekh Agarwal
 Ales Tamchyna
 Alex Grubb
 Alexander K. Hudek
 Alexander Trufanov
 Alexey Rodriguez Yakushev
 Anna Choromanska
 Ariel Faigon
 B. Scott Michel
 Ben Gimpert
 Ben Wing
 Bharath Krishnan
 Brian Muller
 Chris Quirk
 Dan Melamed
 Daniel Erenrich
 Daniel Hsu
 Doug Shore
 Eric Whyne
 Francesco Orabona
 Gabriel Synnaeve
 Gordon Rios
 Hal Daume III
 Harry Robertson
 HaveF
 Hui Gao
 Ivan Dyedov
 Jacob Hofman
 Jaimyoung Kwon
 Jake Hofman
 Jan Szumiec
 Jarrod R Parker
 John Langford
 Jon Morra
 Kai-Wei Chang
 Kristian Holsheimer
 Lihong Li
 Luis Pedro Coelho
 Lukas Zilka
 Luong Hoang
 Marko Asplund
 Marcel Laverdet
 Martin Popel
 Martin Thomas
 Matthew Hoffman
 Michael Brundage
 Michelangelo D'Agostino
 Monami Sharma
 Nick Nussbaum
 Nikos Karampatziakis
 Nirupama Chandrasekaran
 Olek Zendel
 Olivier Chapelle
 Parag Agrawal
 Paul Mineiro
 Paulius Klyvis
 Priska Herger
 Qiao Mu
 Rob Zinkov
 Roy Frostig
 Rukshan Batuwitage
 Sam Lendle
 Sam Steingold
 Selim Raboudi
 Sergei Matusevich
 Scott Graham
 Sharat Chikkerur
 Shravan M Narayanamurthy
 Siddhartha Sen
 Stephane Ross
 Stephen Merity
 Tim Cowlishaw
 Tom De Coninck
 Vaclav Petricek
 Vladimir Vladimirov
 Werner Fenchel (not really)
 Xavier Daull
 Yaroslav Halchenko
 Zach Mayer
 Zeno Gantner
 Zhen Qin