You have a program called Google books downloader. But even if you try to download most of the books are not whole. Google or Amazon give you preview consisting of couple pages up to 30 or so, or you can see ever 6th page etc. So there isn't a way to download a whole book. Unless somebody scans it and puts it on the internet. However it is interesting question. So I'm looking forward to other answers, maybe I'm wrong about this. I'd also like to download a whole bunch of books. I don't think it's laughable. It's a good idea. Why not just put it on paper. Better to say stuff in one way or another than not say it at all. I sometimes write letters to my friend because I suddenly feel like talking but I forget fast what I wanted to tell her the next day. So I give her a letter. And she thought it was awesome and started to write back. And we live few kilometers apart.
This isnt really the forum for pirating books. I can however tell you that torrent sites are your answer and search Epub