Essential Extras - and why

[Xenedis]

What extras do you find essential for your photography and why?

Here are some extra items well worth considering, especially if you're a dawn/dusk seascaper:

1. lens cleaning cloth;
2. lens cleaning pen;
3. air blower;
4. plastic bags to cover the camera in the rain or near the ocean;
5. towel; and
6. headlamp for low-light.