Peter Cohen, writing for iMore, talks you through the process of adding spacers into your dock, creating natural groupings for all your dock icons.
I really like this idea, though I wonder if there’s a way to add an additional hairline to the dock, like the one on the right side of the dock, just to the left of the trash can. Anyone know how to do that?
Bit of a kludge I guess, but you could put a folder in there where the folder icon is that hairline or whatever you want.
For a solution without the terminal (using the same commands), try this instead: http://stormbuster.tumblr.com/post/119520832405/a-friend-just-asked-me-how-to-add-those-nifty A friend asked me how to do this, and I figured 10 minutes of my time with Automator was enough to create a one-click solution.