Could you make a rainbow border? Eleanor Burns did that on her sampler number one which aired last Friday. You take your left over strips and sew them together in a pleasing way, and then you cut them apart at the width plus seam allowances that you want for the border. If you didn't have quite enough strips to do that you could add a couple of different fabrics in colors that match as well.
http://www.sewntogetherquilters.com/...t_pattern.html The link will take you to a border like the one I'm talking about.