Check out Nate Silver's latest posting on fivethirtyeight.com to see just how much of a "swing state" New Hampshire could be in this year's Presidential election. Silver makes the case that even though Arizona could be close, it is not a swing state.
He produces a map which has Obama winning Arizona to get to 278 electoral votes. In the scenario, he has Obama losing New Hampshire. If you take Arizona's 11 electoral votes away from Obama on the Silver map, he'd be down to 268, but then if you add New Hampshire's four votes back in, he'd be back to 272 (270 of course is the winning number).
That's just one of several scenarios in which little ol NH could decide the election as we did in 2000 (don't tell Floridians that).