This is a list of a bunch of essential tools you may need while out in the field.  While some of these are helpful for collecting, I primarily use them  to make it easier to take pictures.  This is not a complete list but gives a pretty good idea of what may be in my backpack or car.

Hook

Tongs

Potato Rake

Camera w/ extra batteries and memory

Tripod

GPS with compass and altimeter

Plastic bins/bags for amphibians

Snake bags

Field Guide

Dip Net

Flash light

Delorme Gazeteer and topomaps

Field notebook

Cell phone

Water

Toilet paper

Permits when applicable