Sources:

ArchNet
Information on archaeology maintained by the Archaeological Research Institute at Arizona State University.

ArVix (Cornell University)
Open access to 730,133 e-prints in Physics, Mathematics, Computer Science, Quantitative Biology, Quantitative Finance and Statistics.

H-Net (Humanities and Social Sciences Online)
H-Net creates and coordinates Internet networks with the common objective of advancing teaching and research in the arts, humanities, and social sciences. Also sponsors over 100 free electronic, interactive newsletters ("lists") edited by scholars in North America, South America, Europe, Africa, and the Pacific.

Highwire
Access to articles and journals in the natural and life sciences.

Popular Science
Digitized editions of Popular science, a monthly magazine covering general-interest science and technology topics.

PubMed
Access to articles and journals in biology of medicine. Run by the National Institutes of Health.

Science.gov
US Government portal for all things science and technology.