While this isn't breaking news, I finally got around to actually looking at this and "testing the waters".
I was pleasantly surprised to find that even very rare books can be found online through the Library of Congress now!
I went to the Archive site and typed in a search for "Abraham Lincoln" [minus the quotes]. This gave me literally hundred of possibilities. Including the massive "Works of Abraham Lincoln", all 14 volumes! These are available to not only read online, but can be downloaded in PDF form and read later on your computer!
I hope you'll take a few moments to explore this, try a search for texts with your family's surname, or just look for your favorite author!