Echo & Co has a great guest blog post about using Google's free adwords for non-profits to test and refine the messages you use.
What words resonate with the people you are trying to reach? Does some language work better than others to move people to take action? These are difficult questions for many non-profits to answer. At a recent workshop in Portland with the NonProfit Association of Oregon, I recommended using email and Facebook campaigns to test different strategies and refine messaging before integrating it throughout your communications. To that list of easy and free A/B tests now comes Google's Adwords.