Each one=1000 words
There’s a new free images database available from NCBI (the National Center for Biotechnology Information, aka the folks that bring you PubMed). Imaginatively entitled Images, it allows users to search millions of scientific images from NCBI full text resources, including images from journals in PubMed Central. Search with terms or detailed search parameters, such as image height, width, and caption. Try “squamous cell skin cancer” for some fun results.
You can access images from the Database drop down menu in PubMed, directly at http://www.ncbi.nlm.nih.gov/images
*Edit* July 2011 This database is no longer available from NCBI. Try searching under PubMedCentral and images will be on the right side of the screen.