I have a 750 gig portable drive. It holds pdfs of military manuals on nearly every subject that you can imagine, medical and pharmaceutical manuals including "where there is no doctor" and "where there is no dentist", books on farming, gunsmithing, manuals with exploded diagrams of almost every firearm that you can name. I have the Declaration of Independence, The Constitution, the Bill of Rights. I have pdfs on mechanics and auto repair, boat building, blacksmithing, mining, smelting, chemistry, engineering, math, history, psychology, text books and on and on. I have over 400 classic novels and books just for fun, the complete Shakespeare, all of Poe, all of Kipling, all of the Foxfire books, The Lord of the Rings, tons of S. King, tons of Robert Heinlein, Burroughs, Robert E. Howard, The Oz books and many more. I have just under 200 digital movies and adding more all of the time. I have tons of U-tube how-to videos and adding to those all the time.
Portions of my library are also copied onto Data Cards for use in either a Galaxy Tab or an Eotac e-reader that is old but works very well in black and white. I am getting a terrabyte drive to copy everything onto so its not all on one device.
We have a Dell mini Insperion that lets us view anything on the large drive. Its not fast but can be charged in the field, its light and compact. Great for reading files or watching movies.
The most difficult part is keeping all of this information organized. I consider this "SPARC" drive, Survival and Preparedness Archive (not my idea but I love the title) to be one of the most useful survival tools that I have. Friends have added to, edited and organized it. Its compilation was a lot of work and is ongoing daily.