I use this app for mapping various trackpad gestures to hotkeys and actions as well as quick one to one hotkey mappings for various apps.
I wrote about how I use the app to heavily customise my gestures in detail in an article here.
I mostly use the app to set one way keybindings. That is single key -> key app specific bindings like this one :
And to set up app specific and global gestures. Like this one :
You can view a printed version of all the bindings I have made here and you can download the preset I use to try some of the bindings I have made for yourself by importng my preset to BetterTouchTool.
Here are some images of the gestures I use.