Since the inception of the color coded homeland security advisory system, I have thought it to be useless. First, the colors and ratings mean nothing to the average individual. Also, why advertise to potential terrorists that we are or are not on a "heightened alert" status? It is not like the ozone level reports during the summer on your favorite weather forecast.
Being prepared is a good thing and is the responsibility of every citizen. The nation of Israel takes this seriously, since they deal with terrorism more than any other country. There is some good information on the Homeland Security web sites.