The American Memory Project
Access 
Data access and download is completely free and open to the public. Many links are provided, pointing both to internal and external pages (and fully downloadable)
Fee Policy 
Documents, both textual and multimedia, can be easily and fully downloaded for free - no subscription is required
Free Retrieved Material
All records are free and the only limit to the use of retrieved material depends on the general laws on copyright
Linking Richness
Internal links are many and well organized; they cross through different areas of the website, allowing to get the same information starting from different points. External links are also rich, directing to other federal institutions, libraries, universities and private digital collections