I just found a site called Forgotten Books that has several free ebooks (pdf format) available for download. I wouldn't have taken the time to mention this, but I thought I would browse the site and found a collection of John Calvin's Commentaries!
I just downloaded one of these copies to take a look at it, and it wasn't horrible. Their free books are not in high quality, so it looks more like a copied version of an actual page out of a book. Personally this didn't bother me, but the book wasn't searchable which would make finding things a little more difficult. But I guess if you know what you are looking for it wouldn't be that big of a problem. Besides, since when did the idea of a searchable book become essential?