The very nice example of data visualization came from SpringerImages - 2.8 million images from Springer articles. Have very nice search across subject and type of a image (video also exists).
It seems that SpringerImages generate new trend - CellImageLibrary a new picture-hub from the National Institute of General Medical Sciences (NIGMS) is supported by Award Number RC2GM092708.
Purpose: This Image Library is a repository for images and movies of cells from a variety of organisms. It demonstrates cellular architecture and functions with high quality images, videos, and animations. This comprehensive and easily accessible Library is designed as a public resource first and foremost for research, and secondarily as a tool for education. The long-term goal is the construction of a library of images that will serve as primary data for research.