Pubmed. Easily searchable online access to essentially all primary scientific articles that pertain in any way to human health or disease. Abstracts for nearly all articles are available online. This is the place to go to quickly identify not only the key scientific papers, but also the key scientists.
Issues in Science and Technology. This journal is published by the National Academy of Science and others and it contains eminently readable articles on public policy and science, written by top-flight scientists. Its a great place to go to find a broad and understandable overview.
Science Netwatch Archive. Eclectic collection of interesting web sites, many rather technical. See especially the Science Policy, Science and Business and Ecology headings.