Do you want to keep the Dock in OS X organized? You can do this with a blank space. This way, you can divide your Dock in different groups. Copy and paste the following command in a Terminal window. After the restart, the space will be added to the Dock, which you can move to any place.
defaults write com.apple.dock persistent-apps -array-add '{"tile-type"="spacer-tile";}'; killall Dock
You can remove the empty space in the same way as deleting an app from the Dock.