Campanula was my first thought :-) C. garganica 'Dickson's Gold' would be a great choice. Better behaved than many of the other creeping campanulas, this holds its intense chartreuse color well in shade. I have it planted in a shady rock wall myself. Woodland phlox, Phlox divaricata, would be another possibility.

Yes, me, too, Campanula! C. poscharskyana is one of my all-time favorite plants. It withstands shade, blazing hot sun, has lovely blue flowers and is even evergreen.
What more could one ask?!

CathyJ
Olympia, WA

And there's Campanula 'EJ Frost' in near white, for a change. But unless these campanulas are grown in the cracks of the wall itself it will be bare again after you remove the spent flower stalks in summer. The foliage is neat and tidy, not draping.

If the soil stays moist, Chrysosplenium davidianum is a nice draper, and also Chrysosplenium macrophyllum, whose runners might look nice hanging from a low wall, as could those of Saxifraga stolonifera. Kenilworth ivy is also good for that if you're looking for a quick fix but it's agressive. A shade tolerant cranesbill like Geranium macrorrizum will, in a couple of years, spill over a wall too, but again, agressive. Shade is the limiting factor here.

Let's see--- what is draping over my shady walls, besides what Brody mentioned?
Native Tolmiea menziesii, piggyback plant and it's cultivar 'Taff's gold' should work since it can be planted into macrame hanging baskets.
How about Rubus tricolor?
Euononymus fortunei will drape over things.
Some of the toad lilies are arching.
and Foam flower, Tiarella 'Running Tapestry' will send runners over a wall.

Sounds like situation is pretty dark, not sure all those would produce the desired effect. Additional details would make it easier to tell.

My grandmother had a piggy back that fascinated me in a macrame hanger in her living room for many years. Thanks for the memories. :)

Some ferns and hostas would drape a bit though not as much as an actually creeping plant, what about vinca?