not sure how low-growing you need but these have all done well for me..snow on the mountain, vinca vine, crown vetch, wild ginger, pachysandra and creeping charlie (just kidding about that last one but it does do amazingly well!)

A very belated "thankyou" to Birdwing. The crown vetch sounds very pretty, but maybe it would take over too much. I like the vinca vine idea also.

Alas I am still undecided what to do. I'm a quick decision maker, not! I have a 3x15 foot raised bed in front of a retaining wall that I want to be low maintenance, but don't want it awash with just one plant either. Hence the need for a groundcover, maybe it could smother some weeds for me while allowing me to have fun with other plants as well. I put in a few Partridgeberry plants last year, but I did not do a good job watering them so I don't know if they are alive. Maybe I should try some more of those, those are very low growing.

Canada violet and other wild violets, Virginia Waterleaf, Wild Ginger, Sweet Woodruff, Bloodroot, Starry Solomon's seal, Epimedium, and Pachysandra procumbens are good choices.
Snow on the mountain, crownvetch, vinca minor, and creeping charlie are really invasive and can spread out of the garden and become weeds in natural areas.
There are many, many kinds of woodland wildflowers and low growing sedges that don't spread but can be planted close together that can make for a nice diverse ground cover.

Ajuga? Nice color variations, looks nice with violet mixed in, hardy as hell...

Thanks for the additional ideas! One more question, since this in a retaining wall and a contained bed, do I need to worry about it being invasive? I guess it could climb up the back of the bed (rock wall) and into the lawn? Then again I have such a lousy lawn there, so many tress, maybe that wouldn't be a bad thing? Any other ways it could prove invasive in this relatively contained area? What else can you warn me about so I know what I'm getting into with say Creeping Jenny, which I think would work well for my purpose.

P.S. some of those other suggestions are new plants to me, so I'm looking them up. The Pachysandra procumbens is very sweet.