Those Steve listed are nice.
Additionally, brunneria, astible, hosta, hellebore, heuchera, foam flower, sweet woodruff, ligularia, toad lilies, variegated false solomon's seal, pulmonaria, columbine, vinca, epimedium, forget me nots, viola, touch me nots (reseeds), to name a few. Early bulbs, bluebells...
Consider designing by foliage instead in shade and punching it out with a few annuals each year like impatiens, coleus, vinca, begonia, cyclamen or whatever specialty you might find. Also, you might consider the subshrub category like hookeria, skimmia etc. Also dwarf shrubs and gingers, groundcovers.
Also some larger plants like kerria japonica, oakleaf hydrangeas and other types, viburnums, kalmia, rhodies, pieris, azalea.

Pick your pallete but it will be a different mood than a bed of annuals that bloom all season. However, now you could have something going on four seasons. Consider persistant berries, evergreens, twig and bark color, seedheads and fall color.

Until you grow them you can have no idea how beautiful a late winter early spring woodland garden can be. The first signs of new life often appear shortly after the new year. And through February and March the show unfolds, fresh leaves and the first flowers. The four month show is as long as the summer to follow and sends me out every day in all weather. Check for sale woodland plants now, just plunk them in and see what they do.

My favorite way to find new plants is to visit botanical gardens. The NY Botanical Garden in the Bronx is my favorite of the ones I've visited. The perennial garden near the conservatory has so much beatifully diplayed in one spot. It is worth going in any season including winter.

1. Wait for the frost to kill the tops.
2. Cut the tops off a few inches from the ground.
3. Dig them up.
4. I wash all the lose dirt off in a bucket then let them air dry on some newspaper.
5. Once they are surface dry like a firm potato - I don't let them shrivel - I pack them in a ziplock bag with little air just like that with nothing else. If the tuber group is too large, I've used zipper bags that linens come in or tied tightly other plastic bags. Those thinner bags, I double pack one bag in another.
6. I label the bags and just place them all in another larger bag. I keep mine in my uninsulated attic where it gets cold during the winter. It gets warm too even in the seventies during the day sometimes but they do OK. A friend did this in her attached garage with the same results. I think she put her bags in a cooler.
7. I check on them every once in a while. White fuzzies on some white roots are not bad. I get a little of that. In the spring, they will start trying to grow. There is some leeway here. You don't have to pot them up right away but once the temps stay near forty, I might pot them up or put them in the ground. My friend forgot hers were in the cooler and didn't put hers into the ground until summer. They lived and bloomed anyway.
8. I feel it is easier to divide in the spring if your going to do that. The stems are softer and easier to cut into plus you can see the tubers better and the eyes. Additionally, I think not having the cut marks during storage lessens the chance for infections.