A screen capture of Grognok from Bungie's "O Brave New World" ViDoc.
Grognok is the name of a collaborative world building tool used by Bungie to create maps and locations within Destiny.
Grognok was described by Joe Staten as being innovative world-building software allowing a large team of engineers, environment artists, modelers, and creative designers to work on a world at the same time.
The term "Grognok" was trademarked by Bungie in December 2009 and described generically as "Computer programs for editing images, sound and video; Computer software development tools." (further trademark information available here)
During the Bungie panel at GDC 2013, footage of the Grognok world editor was shown being used to create a base on the Moon.