OMNI Organising Medical Networked Information
Healthfinder (r) - a gateway consumer health and human services information web site
These two sites are both general medical search sites. OMNI is British and Healthfinder is American. They are both very good as they give relevant, reviewed sites in response to a query rather than links to thousands of sites which give useless or even wrong information if you use the big search engines.
Lots of good relevant information and high quality links to other cancer related sites
Macmillan Cancer Relief - Home Page
Providers of nursing care etc to cancer patients
I cannot sing the praises of this hospital enough