In exchance for some "opinions", Crossway will give you a digital (epub, mobi or PDF) copy of
Why the Reformation Still Matters by Michael Reeves and Tim Chester.
I used the scare quotes because this is totally an advertising push poll. "How many Bibles do you own," followed by "would you be interested in" four different ESV Bibles, two that exist now and two that will be available in a few months. As advertising, it worked on me, since I didn't know about any of the four. None of them have digital editions yet, but now I'll watch.
No email address or other identification needed. Answer a few questions, then click the links at the end.
Crossway's
"opinion" poll for the free book.