With the growing nuclear threats from China, North Korea, and assorted Muslim terrorist groups, it is important to get prepared for surviving radioactive fallout. At the minimum, I think that there is a very high likelihood that at least one sub-critical mass radioactive “dirty bomb” will be be set off within the continental U.S. sometime in the next 10 years. Near term worst case: One or more of them go off on September 11th. (Two weeks from now.) Plan accordingly. Study the prevailing wind patterns. Get a copy of Nuclear War Survival Skills . (It is available for free download from the good folks at the Oregon Institute of Science and Medicine , so you have no excuse not to have a copy on your bookshelf!)
If you have a big budget build yourself a fully equipped blast shelter with HEPA filters. But even if you budget is austere, you should at least buy some potassium iodate (KI) tablets for thyroid protection. The thyroid gland is the most susceptible part of the human body to radiation. Thyroid damage or cancer can result even in a low level radiation event (such as what Western Europeans were exposed to when Chernobyl melted down in 1985). OBTW, I was TDY in West Germany at the time, and did not have KI available. I knew enough not to drink fresh milk, but I still felt very vulnerable.
Potassium iodate works by saturating the thyroid gland so that radioactive isotopes will not accumulate. (Thus minimizing thyroid damage.) Do not take KI until just after you have heard of a radioactive release upwind. Long term use of KI can actually cause thyroid damage! KI tablets are available from ReadyMadeResources.com  and several other Internet vendors.