The Copyright Slider allows you to decide if a work is protected by copyright and published first in the U.S.A.
The 108 Spinner joins the Public Domain Slider as a great online copyright tool.
Exceptions for Instructors assists in identifying if an intended use meets the requirements set out in the copyright law.
The Fair Use Evaluator can help you decide if you are using copyrighted materials "fairly" under the U.S. Copyright Law.