Another great book I read (or re-read) over Christmas was "The Great Divorce" by CS Lewis. This is a really interesting view of the after-life and what it is like. It's not meant as a systematically correct understanding of the life beyond death but it is very though-provoking. It's basically the (imagined!) experience of a man who sees both heaven and hell after death and how they operate. Both are presented in very striking ways.
A qualification first: though I love this book in lots of ways there are a few things about it which are left very unclear. For example, Lewis views Hell (and Heaven) very much as an extension of individuals' personal choices into all eternity. This is very insightful on many levels, but it's inadequate if made into the central principle for understanding heaven or hell. The danger is that God's grace and judgement disappear into a karma-like after-life, where my destiny hangs more upon my good or bad choices rather than upon God. A further problem is the tendency towards a Platonic view of the afterlife where the notion of resurrection on a renewed earth is marginalized.
That said, I think there is much here that is very thought-provoking. Heaven and Hell are basically seen as the ultimate extensions of life in this world. Both echo this world but in opposite ways. Lewis's narration starts with his character in Hell. It is strikingly described as a kind of empty, dark and formless town where people live, "the grey town" (p.8). It is a huge, shadowy, dark place - and seems very deserted, "the parts of it that I saw were so empty. Was there once a much larger population?...." He is told, " "Not at all", said my neighbour. "The trouble is that they're so quarrelsome. As soon as anyone arrives he settles in some street. Before he's been there twenty-four hours he quarrel with his neighbour." (p.10)The 'town' is so big because people cannot get on with each other. They quarrel with neighbours as soon they move in. Everyone is trying to get away from everyone else and so they move away from one another. Thus, the 'city' is always expanding but feels increasingly empty because everyone is trying to get away from everyone else. This town is not a place of gathering, rather it is an incredibly lonely place. Lewis gives us a depiction of individuals who are totally self-absorbed and foolish, unable to form relationships but constantly seeking to dominate one another. The irony of the place is that "they have no Needs. You get everything you want (not very good quality, of course) by just imagining it." Hell, counter-intuitively, actually brings the satisfaction of of our desires in a way that never really satisifes. We get what we want but find that it was never what we wanted. The essence of Hell is made clear as the book goes on. Hell is really an insubstantial place, incredibly small (though it seems big when you are there), dark and self-absorbed. Some of the characters from Hell get, in the story, to 'visit' heaven and they find as they get there that they can't walk on the grass and the lightest stone weighs tonnes for them. They are simply too insubstantial, "one had the feeling that they might fall to pieces at any moment if the light grew stronger." (p.17) Above all, Hell is depicted by Lewis as cursed and nightmarish, but the nightmare is a self-imposed, self-centred prison. Evil essentially makes people mundane, irrelevant and ghost-like.