You have a beautiful home. :)
I found a linky on slug detterents etc here:
http://www.gardenguides.com/pests/tips/slugs.asp

apparently, slugs dont prefer ginger, garlic, mint, chives, red lettuce, red cabbage, sage, sunflower, fennel, foxglove, mint, chicory.

considering the shade, maybe not the sunflower, and i wouldnt plant the foxglove near the edibles.
mint makes a great ground cover..it takes over though.

possibly incorporate a rain garden in this area as well?. (but it would have to be placed at the top of the slope because its flat).

The rain garden will keep the runoff from the roof from going into the street, and it will naturally filter the sediments out, also a great place to attract birds, frogs and dragonflies. :)

Slugs natural enemies are birds and frogs.

Thank you, that is excellent information.

I started looking into those plants. It seems like mint would indeed thrive - but does anyone have any comments on whether it looks weedy?

Can't do ginger; it's not frost hardy.

Chives - looks like I can edge the top of the slope with chives.

Sage - looks like I can also do this. But starting to wonder now how to figure out if all these plants do well in combination, and how exactly to design the slope.

Fennel also looks interesting to me. Will all this stuff look fairly good and not like a weed garden? Sorry, I've never grown herbs before and not sure how it all looks (all the photos I see are of cuttings and not full gardens).

fair warning most sage plants don't like a lot of water. I have to grow my sage indoors here in rainy humboldt county in CA. Mint loves water! I don't think it looks weedy, but I might not be the best judge. =)

I'm late getting into this discussion....

All of those plants listed are herbaceous and die down to practically nothing in winter. Nor do most of them have a particularly strong root system. I am visualizing very wet, unsupported soil sliding into the road.

You don't indicate that you want the yard to be 'useful', so may I assume you just want it stabilized and to look decent?

Here are some plants that slugs don't like, but they seem to be mostly ornamentals and herbs:

Almost any plant with hairy leaves
Acanthus (BearÂs Breeches)
Anemone x hybrida, & Japanese
Astilbe
Astrantia
Begonias
Bergenia
Bleeding heart (Dicentra)
Catmint (Nepeta)
Columbines (Aquilegia)
Corydalis
Crocosmia
Daylily (Hemerocallis)
Euphorbia
Ferns, all
Foxglove (Digitalis)
Fuchsias, hardy
Geranium, hardy
Geum
Globe thistle (Echinops)
Grasses, ornamental
Hellebores
Hydrangeas
Knautia
Ladys mantle (Alchemilla)
Lavenders
Lilium henryii
Linaria
Lungword (Pulmonaria)
Lysimachia
Meadow rue (Thalictrum)
Meadowsweet (Filipendula)
Monkshood Aconitum
Penstemons
Peony
Phlox
Phormium
Polemonium
Polygonatum
Poppy, oriental
Potentilla
Primulas
Rosemary
Roses
Rudbeckia
Salvias
Sea holly (Eryngium)
Sedums
Shasta daisy
Stachys
Verbascum
Wallflower (Erysimum)
Wild strawberries
Yarrow (Achillea)
Yucca

The ones that still have a presence in winter are some of the ornamental grasses, peegee hydrangeas, lavender, rosemary, potentilla, roses, sedums, and yucca. You would have to check to see which ones are hardy in your area, and would tolerate your soil.

You could plant some of the herbaceous perennials among them, but they would disappear from the surface after a good frost, but show up in spring. And there are some annuals that would probably reseed themselves naturally and shift around from year to year.

If you wanted to put a small amount of effort into controlling the slugs, use a product like Sluggo, checking to see that it's first ingredient is iron phosphate, which is non-toxic to children, pets and earthworms, and breaks down into a soil amendment. It is permitted for organic use, including around food plants.

If you wanted it as no-care as possible, yet look good and stabilize the soil, carefully chosen ornamental grasses would be hard to beat.

A knowledgeable local nursery could be a big help. The Big Box stores would not.

Sue

Devil's club :)