Leading cryptographers and others whose work spawned the commercialization of high-level cryptography are wondering if they did the right thing. They are haunted by the idea that law enforcement agencies may have figured out what the terrorists were planning, if only powerful encryption techniques had been kept secret.

A number of health officials and experts are warning that steps being taken by the government and members of the public in response to threats of bioterrorism -- mass vaccinations for smallpox and using antibiotics to counter anthrax -- carry health risks that may far exceed their benefits.

The investigation of the terrorist attacks on the United States is drawing new attention to a stealthy method of sending messages through the Internet. The method, called steganography, can hide messages in digital photographs or in music files but leave no outward trace that the files were altered.

Theraputic cloning, the use of cloning technology for curing disease, is often raised in cloning debates as a positive benefit of human cloning. However, scientists admit the technology is "literally in an embryonic stage."