We made a large planter box for our cement front yard a few years ago. It served two purposes, it gave some greenery to an otherwise paved front yard and secondly it made people aware that it was our property not just a very large sidewalk, and thus in turn got them to stop walking right by my front window. It has worked quite well. We still get the odd person who will take the route up by our window, but generally it gives us much more privacy.
In the spring I have bulbs planted and get lovely spring flowers. In the summer I plant bright annuals which last mostly into the fall.
For the holidays (and the rest of the winter) I like to have some fresh greenery and a little bit of rustic winter charm. So this year I hit up a local grocer who sells Christmas trees and greenery. I purchased about 5 bunches of assorted greenery, and my Mom and I set to decorating the planter. We also had some left over garland from another project. We're not florists, and our only mission was to give it a bit of height and fullness. I also purchased a package of pine cones at my local dollar store, hot glued them to coffee stir sticks, and tucked them in here and there.
We also did a small urn under our mailbox by our front door.
So even though we don't have Christmas lights up (we don't have any outdoor electrical boxes!) it still looks festive. That combined with a wreath on the front door has our storefront in the holiday spirit.