I like to organize my applications in the Dock on OS X. This trick will add a spacer that you can place anywhere to create a separation between different groups of apps:

$ defaults write com.apple.dock persistent-apps -array-add '{tile-data={}; tile-type="spacer-tile";}' && killall Dock

The Dock will restart and you’ll see an empty space somewhere on your Dock. Just drag it to where you want some extra space and you’re good to go.

Dock with Spacers