Here's a blog which is relatively new, being less than a year old, and which simply has downloadable issue of DCs circa seventies 100 Page Giants. The Old Warrior, who owns the Blog started out presenting the various Giants in chronological order and has kept things in publication order. Originally the "100 Page Super Spectaculars" were entirely collections of reprints, and contained some of the earliest reprints of golden age Quality material that some of us probably first encountered. A few years later, when the price of comic books increased once again, the 100 page format spread to some of DC's other titles and it was possible to pick up an issue of "Detective Comics," for example and read a brand new Batman story as well as a golden age Batman classic, a silver age Batman story, perhaps even a golden age Robin reprint from "Star Spangled Comics" or a golden age Alfred six-pager, a Kid Eternity or Doll Man story, a Manhunters of the World story, and an early Martian Manhunter story which is quite a buy for sixty cents. Often there was no apparent rhyme of reason for what the 100 Page Giant format reprinted, but The Old Warrior has provided a table of contents for issue issue, so you don't find yourself uploading issue blindly and can isolate things you would like to read.