Taking Pictures and Making Recordings Around Polling Places

"Documenting Your Vote"
Citizen Law Project.

A pretty good guide for how to not get in trouble around polling places. In a way, it's just common sense:

"Guidelines for Avoiding Legal Trouble
1. Follow the Rules"

This page seems like a pretty good place to start checking what is, and isn't acceptable in your state. It includes a chart that outlines which states have what rules.