Sweet Kate Spiderwort has bright golden foliage and blue flowers. Bergenia has sweet little blue flowers in the spring. Lily of the Valley has fragrant spring flowers. Chelone, turtlehead, has late summer flowers that last through fall. Plumbago has summer flowers and colorful fall foliage. Wild cranesbill is both tough and beautiful. How about some plants that have variegated foliage? One of my favorites is variegated Solomon's Seal. Drifts of hostas and coral bells will also add a lot of color to your shade gardens. For more ideas, Clemson University Extension has a good resource on plants for shade gardens.
Thanks for writing!