You could put out pansies, which like it cool, but not the more traditional summer annual flowers, which cannot take a frost. If you can work the ground, it is safe to sow vegetables like spinach, beets and radishes. For more ideas, check out the cool season vegetables on this list from Penn State's Cooperative Extension service:
Thanks Doug. I also am getting some heleboras (spelling?) from my friends mother to try un the shaded part of my back yard. I love it when people decide they don't want some of their plants anymore!
wait - labor and plants lost to frost is a waste. gardening builds patience, you know. :)
Patience is a virtue that I have never had. I guess gardening will help me to gain some then. :)