First of all, you can't nuke-proof yourself. Although potassium iodide can effectively block your thyroid gland from sucking up radiation, this isn't Fallout - you can't just undo the effects of radiation poisoning, or put up some sort of shield.
But of course, scammers are preying upon nuclear anxieties to peddle potassium iodide tablets (of dubious provenance), claiming they'll protect you from Japanese radiation that isn't hitting you in the first place. So watch out, says the FTC: "Fraudsters follow the headlines, tailoring their offers to prey on current consumer fears and vulnerabilities...public health experts agree that US residents should not buy or take potassium iodide unless specifically notified or instructed by public health officials."
That being said, there are legitimate reasons to have some (FDA-approved) potassium iodide tablets on hand - notably, if you live near a nuke plant (within 80km, says Beyond Nuclear's Paul Gunter) - just in case. But that's of no relation to the current crisis in Japan, so don't be fooled by a scaremongering subject line. [FTC]