hostas! they multiple like rabbits and will fill beds nicely, i love varigated and blue leafed verieties.
Astibile is also awesome and comes in all the colors of the rainbow, reds and pinks are my faves but white and light purples look great in shaded garens because they almost glow, especially when surrounded by silver/blue tinted foliage like the blue leafed hosta.
Coral Bells are also great for primarily shaded plots, they have pretty leaves n greens and burgandies with a relay cool shape, and shoot up tall flower spikes with pink, red or white tiny flowers all over that hang slightly and look like bells!
Ferns, look for species good for your planting zone though as they can be tender...
Bleeding Hearts, there sooo pretty!!!
Japanese Anemone, very pretty little pink/white flowers
lupine is very cool but it doesnt like to be moved, get small and give them plenty of room cause by their second season they dont want to be moved!
meadow rue, very pretty flower tops that look almost like theyve been spray painted in a mist onto the plant.
fox glove is also nix but its a bi anual, you have to let it go to seed as each only lasts 2 years
all those work in zone 6, most are hardy to zone 4 or 5, i belive your a 5/6 borderline state...?