Free OS X app to configure custom gestures for your trackpad

This is easily the most important addition to any new Mac I get, and I use half of the things in this list. I imagine Apple's hardware team must be frustrated by the lack of imagination the software team brings to the new capabilities of things like multitouch and force touch. BetterTouchTool rectifies that by giving you the ability to assign an almost infinite array of actions to different gestures. Apple should buy it and build it into the operating system.