I went shopping for some camera accessories yesterday. I got a battery pack attachment for the D300, a cable release, and a flash diffuser. While it might seem like an odd combination, I had reasons.
Wonderful Husband has large hands. He cannot use the pop-up, built in flash on the D300. His hands get in the way of the flash and there are horrible shadows on the pictures. This means that I've got even more reason to never use that flash and I must be ready to use the other flash instead. But that flash gives red-eye all around. To decrease the red-eye, you need to put a diffuser on the flash.
When you are holding a camera to take portrait shots a lot, you can get frustrated with the way you have to wrap your hand around the camera and try to hang on and hit the shutter. The battery pack not only adds battery, it adds a shutter button where you need it. And it also makes the whole camera larger and I hope easier for Wonderful Hubby to hold.
The cable release is just so I can have a little less shake when using my tripod.