And I am trying to think of blue ones to represent a flowing stream.... I hadn't thought of Ajuga.

Take a look at some of the Heuchera's, the vast array of colours is amazing, you'll be spoilt for choice!

Have a look in the A-Z at the foot of this page and click on Ground cover to find what others members have. Heuchera Regina is only 10" tall and has purple foliage.

Louise bought a new plant for ground cover that might fit the bill - called Acaena 'Blue Haze' - more purply-bronze foliage, though. Very pretty leaves, and low to the ground.

Sheila, i'm just going to plant a bronze sedum today, it's Sedum spurium 'Dragons Blood'.
I'll post a picture right now :-))
Lovely dark bronze leaves :-))

A deep purple, almost black =Ophiopogon nigrescens.
Viola riviniana 'Purpurea Group'
Oxalis Xalis 'Black Velvet' - questionable hardiness

I found a list of black plants, some leaves, some flowers
http://www.organicgardening.com/feature/0,7518,s1-5-18-944,00.html

what about persicaria Red Dragon and some of the heucheras?