I've said before that Greg Boyd has produced some really good arguments on the Open View of God. Greg's got a great post on his blog from about a month ago (OK, so I'm a little behind) briefly outlining three really good reasons why determinism (a la Calvinism) is logically untenable. Go check it out!
Greg is actually responding to a previous New York Times article entitled Do You Have Free Will? Yes, It's the Only Choice. This amusingly-titled report looks at some recent psychological experiments that suggest that people seem to believe in a moral responsibility for one's actions that only works if one had, at least at some level, a choice whether to do them or not. They have shown that people who are convinced they have free will, tend to behave better (that is, more socially-acceptably) than people who are convinced they have no choice. It's an interesting study.
Of course, my favorite summary of the whole argument is: "You have chosen to believe in predestination, and I am predestined to believe in free will." Drives my Calvinist friends nuts!