I have stood over a year ago before the election, zuzulegen an SB-400 or SB-600. Because of the size, the choice fell ultimately to the SB-400 and I have not looked back. The flash is much stronger than the built-in flash of my D80 and sufficient for typical inner motives at private parties or the like completely out. Only with photos during a wedding I needed a little more power. He also invites to fast, especially when is not flashed at full strength.
The SB-400 is in perfect harmony with the metering of my camera. You can swivel the head well up and so can be either flash indirectly - or with some craft skills even a diffuser grow (Tip: tack adhesive Velcro tape). The flash fits into your pocket and is extremely handy.