As of September 2015, websites for Michael P. Maddux, P.A., The Law Office of H. Michael Steinberg, and Broden, Mickelsen, Helms & Snipes offer sample character letters to judges. At the Maddux site, the Character Letter page explains the process of writing such letters. A link connects to the sample.
The Steinberg Law Office website presents guidelines and samples for both general character letters and character letters for sentencing. The website of Broden, Mickelsen, Helms & Snipes provides an overview of a character letter, along with instructions on how to complete it. In addition, there is a note to send to family and friends when requesting character letters. All websites direct writers to forward letters to the attorneys' offices, not to judges directly.