I've thoroughly enjoyed reading Greg Boyd's book God of the Possible, in which Boyd lays out a very strong textual-based argument for open theism.
To be honest, I didn't know much about open theism before reading the book. All I had ever heard was that open theists assert that God "doesn't know the future" and that the future is therefore not yet determined.
Boyd's brand of open theism doesn't go that far, and it is the restraint in his viewpoint that appeals to me. In short, Boyd argues that, while God must experience time in much the same manner that we do, God also knows all of the possibilities of the future. He determines, based on that knowledge, certain things that will happen with absolute certainty. However, the future is not exhaustively determined. That is, there are some things that God has left to the free actions of humanity.
Boyd, who writes as always from an evangelical viewpoint of scripture, is mostly concerned with making out the case that his viewpoint is compatible with scripture. I was easily sold on it. The viewpoint of classical theology, which holds that God has absolute foreknowledge of everything that will happen in the future, just doesn't fit with the descriptions we get in scripture – where God is frequently surpirsed, taken aback, even sorrowful for the things God has done.
To be honest, I wasn't so much left thinking "Wow! that is interesting and new!" as I was thinking "Yes, of course thats it. Nothing else really fits what you read in scripture." In other words, Boyd hasn't so much "sold" me on his perspective as he has given me a vocabulary to describe what I suspected was the case all along.
Boyd doesn't seem to have much interest in creation theology (i.e., the idea that God's redemptive move is to renew creation), at least in this book, but I think the open perspective fits it quite well. How is God to delight in, be surprised by, and wring his hands over our world and its people if the universe is doing nothing other than playing out a clockwork script that God has already written and that knows in every detail?
I recommend this book to anyone who has struggled to make the square peg of "divine foreknowledge" fit with the round hole of the God that we encounter in scripture.