Medcyclopedia

Amersham Health's Medcyclopedia includes, free, all text and images from The Encyclopaedia of Medical Imaging's eight book volumes: Physics, Techniques and Procedures, Normal Anatomy, Musculoskeletal and Soft Tissue Imaging, Gastrointestinal and Urogenital Imaging, Chest and Cardiovascular Imaging, Neuroradiology and Head and Neck Imaging, and Paediatric Imaging. 17,000 topics, 8300 images.

The site notes that you are free to copy text and images for non-commercial use in lectures, articles, etc. provided that you refer to the source (http://www.medcyclopaedia.com, Amersham Health).

Good deal.