Betty & Gordon Moore Library Scan and Deliver service
ISIHighlyCited.com, a free, publicly available website intended to highlight the world's most cited authors from the last two decades and to create a network of highly cited researchers across diverse disciplines.
Pubcrawler, , a free "alerting" service that scans daily updates to the NCBI Medline (PubMed) and GenBank databases.
Scopus, abstract and citation database of peer-reviewed literature and quality web sources
Europe Pubmed Central, free archive of life sciences journals