Digital Cameras are very useful to digitize anything at any time, such as documents in special collections, where they won't let you xerox anything; government archives, such as NARA; Libraries such as the NYPL or LOC, where they charge too much to xerox; In stores while browsing magazines and you see an article of interest, but you dont want to buy the whole magazine just for that article; in libraries, where you don't have borrowing priviledges; Online, where the website has blosked downloading or copying and pasting, which Google books does for it's copy right books. In this case, you can take a shot right off the screne, and it will be a jpeg file. Then you can convert those jpegs into PDFs and then OCR them.
There are many good digital cameras, but one of the best is the Nikon Coolpix L20, which I have. It has 10 megapixels capability with a 3.6X zoom. You can hold it with one hand while turning pages, and has an anti-motion method, such that slight movements of your hand will not mess up the picture.
Batteries for the Nikon Coolpix L20: Alkaline LR6/L40; or Lithium FR6/L91. With "Energizer" batteries, the type is "Ultimate Lithium" and is available at Walmart;