I'm with Shane,
I generally pile the leaves on my beds for the winter, then dig them
in to the soil in the spring. I can't think of anything that would
grow during the winter. Sometimes the pansies survive over winter and
will remain sort of greenish, but they don't look all that pretty
during the winter months. There are things that could provide green
ground cover during the winter months (like low growing junipers and
Oregon grape holly, but you wouldn't want to put them in just to dig
them up in the spring.
Chad