Museums
Deutches Museum Museum of Science and Technology in Munich, Germany.
Species Archive Vast database of images and sounds of life on earth. Contains information on extinct species and also those on the endangered list. 

Biotechnology
National Center for Biotech Information Established in 1988 as a national resource for molecular biology information, NCBI creates public databases, conducts research in computational biology, develops software tools for analyzing genome data, and disseminates biomedical information - all for the better understanding of molecular processes affecting human health and disease.
Kyoto Encyclopedia of Genes and Genomes KEGG (Kyoto Encyclopedia of Genes and Genomes) is a bioinformatics resource for understanding higher order functional meanings and utilities of the cell or the organism from its genome information.
   

Chemistry
Virtual Chemistry From Oxford University
   

Miscellaneous
Scientific American Home site for Scientific American Magazine.