Something that was already in Logic 7 (and most DAWs as I know of by now) is colorization of tracks. The handy keyboard shortcut in Logic is option-c. This will open up a palette of colors. If you have one or more regions selected, and choose a color, this will be assigned to each one.
Now, if you double-click on the actual palette elements, you get a color chooser, so you could further define what colors are present in the palette.
My main motivation to use this is that I like seeing big patterns, especially when the canvas area is crowded, or otherwise zoomed out. I usually specify certain colors for certain regions: blue for drum regions (can’t live without them), red for bass lines. Now when I think of it, I should use white for solos and melodies, so it’s red, white and blue!
Anyway, similarly, you could use certain base colors to define certain sub-groups of regions, and based on such color meta-info you could quickly get the big picture of the current track content.