How about liriope muscari? It will do well in shade, will grow to about 6" in height, but can't handle much traffic. However, you can occassionally step on it and seems to be okay.

I would like to throw in a suggestion as for something that would work in a hot area here.

I'm thinking sedum. Would a sedum work down there? I'm thinking of a stone crop variety in particular because it is green with white around the edges....but it doesn't like much stepping on either.

Another idea would be a irish or spanish moss or maybe corsican mint. The mint would be happiest in the warm trampled on area...just be sure to keep it contained because it spreads well in heat. You can propagate easily by *very lightly* blending 1 part plant with 1 part sugar and beer, or I've also heard 1 part plant and 1 part yogurt. You can then take the mixture and paint it on the soil with a paint brush. Let it grow a couple of weeks (no stepping!) and you have an all over ground cover.

Do you think something like this would work? :-)

~D

Mondo Grass. No white except the flowers, but it takes the traffic from my dogs. There are several varieties with different heights and shades of green, including one that is almost black.

Have you looked into pachysandra? I was lucky enough to get free access of just about as much of this as I wanted... so I took quite a lot. I planted it every foot or so in a deeply-shaded part of my garden. Also planted it on a slope and in an area that gets a moderate amount of sun.
Since I had more than 500 plants to get in the ground, I wasn't delicate at all about planting. I just used a hand mattock and shoved them into the holes. I'd say 99.9% of these plants rooted right in and are in the process now of spreading out.
Eventually, they'll form a solid mass of notched green leaves, about six inches high.

Hyperboy

I have pachysandra(also called Japanese Spurge)too. It does well in shade spreds like crazy(some people consider it invasive) and can stand being stepped on. My dogs wear paths through it. If you consider liriope be advised that are at least 2 species. One is a nice clumping plant with pretty flowers(in bloom now in GA) that spreads slowly(I divide mine almost every year). The other is a rampaging rhizomous grass that will take over your yard and has no redeeming features. I can't remember which is which right now but a bit a research should help you figure it out.

Liriope spicata is the runner-it has thinner leaves (?1/4") and is green.

Liriope muscari is the clumper, and is green or varigated. The leaves are broader (? 1/2").

A variegated St. Augustine grass used to be available from Glasshouse Works. You can find their catalog online. It isn't as vigorous as the typical green forms.