Consider variegated shrubs. Not much blooms with so little sun. Aucuba japonica 'Variegata' is one to consider (make sure it works for your zone).

Here is an interesting article on using variegated plants.

The "book of lists" for the mid-Atlantic region is a nice resource when looking for plants to fit a certain situation.

Here is a link that might be useful: Mid-Atlantic Gardener's Book of Lists

I assume the shade is casued by overhead branches on trees? If so, have you though about limbing up the trees to allow more light in? I have a somewhat similar situation and Rhododendrons do well, except they are "green". All greens are not created equal. Find plants, like ferns, which are different shades of green from the dark green of Christmas fern to the lime green of Ostich fern.

Under my cherry trees I grow a hedge that is mixed in foliage color and texture & height. I doubt that any of the hedge gets as little as an hour but I have had very good luck with:
Aucuba japonica, nandina, alleghany viburnum, pragense (sp) viburnum, Diana Rose of sharon. I also grow Schip laurel, otto luykens laurel, euonymous silver knight in shade and several kinds of holly. The problems I have had are as much about dry as about shady.

I have mixed in shade perennials like hosta, verigated solomon seal, ferns of various colorations. Bulbs and pansies for late winter and spring. I noticed acorus had self seeded into the darkest part of it. Lovely verigated foliage with red berries much of the year.

I even grew some smaller japanese maples that provided fall color, although they are now so big that I had to move them out. Some japanese maples are 4-8 feet and can give you a range of colors for spring and fall

In short, there are so many things going on in that hedge that the last thing anyone notices is that it is mainly green.

The main thing I would do differently would be to combat the dryness when I started the whole thing. I really regret not having trucked in a few cubic yards of leaf mold, which the city sells for $15 yard delivered, when I started this to make the soil much more water retentive.

You might get some ideas from 8-page article on using various types of BOXWOODS and HYDRANGEAS in current issue of Garden Ideas magazine (Spring 08). Shows various hydrangeas framed by boxwood borders. Fine leaves of small sheared boxwood borders make great contrast with big leaves of large mounded hydrangeas which fill centers. Discusses growing habits, colors, etc. Contrast in shapes and shades not exactly bright colors, but might worth consideration.