Hell
I’ve been saving this link for a while, waiting for another related link to go with it: Steve Hays examines four different metaphors the Bible uses in relation to hell and discusses what they mean (Triablogue).
Heaven
Andy Naselli recommends Life Everlasting, a book on the subject of heaven by Dan C. Barber and Robert A. Peterson. It’s notable because the authors avoid speculating. That it sticks to what the Bible says makes me want it—that, and the list of questions answered in the appendix.
You can download the table of contents and first chapter (pdf).