I would like an option to personalize pin colors. I didn't find a key telling me all of the existing ones but they seem to be mostly different except for Wherigo and Mystery which look pretty similar.
I don't view this as high priority but it might aid those with varying degrees of color blindness. For what it's worth, I have reassigned colors in Geosphere which has 14 choices for 13 cache types (earth is brown so that color is a good cue for an Earthcache to me). I notice also that non-cache waypoints have their own icons to distinguish them like a checkered flag for Final. Something to think about.