Online Writing Lab at Purdue University
Purdue University Owl: The Basic Business Letter
This lesson from Purdue's online writing lab details both the parts of a business letter and the various formats for one, including block, modified block, and semi-block. Great resource for getting started writing a professional letter.
PBS
Arthur: Letter Writer Helper
This interactive site gives examples of how to write a letter, an email, a postcard, and a greeting card. It even explains how to address an envelope. As students roll their mouse over the letter it explains what each part is called and...