I have pointed you to the Monergism Reformed/Christian book website before, and I do so again today. But Monergism has ramped up their free ebook service and this time I want to highlight that benefit of their ministry (They also have scores of other free resources too – mp3 files, pdf articles, etc.).
The link above will take you to the page where their free ebooks are listed (in multiple formats for most ereaders). There you will find a number of great classics there, with others being added weekly. So you will want to bookmark this page, and check back frequently.
Below is the little image and introduction Monergism has for these resources.
The Three R's Blog 