International Personality Items Pool
There's definitely some technical jargon here, but if you're studying the effectiveness of personality testing, it would be hard to find a more complete resource.

Northwestern University's Personality Project
A great place to start to learn about personality theory and the pros and cons of personality testing.

University of North Carolina's Personality Testing Resource
A short list of resources that both explain and give examples of how personality testing can be beneficial in the employee selection process and in broad HR initiatives.

The United States Air Force Occupational Measurement Squadron
Want to see how the military designs tests to select and promote applicants to specific jobs? This page provides links to the occupational assessment, test development, and career development wings of the Air Force.

U.S. Army Research of Performance Prediction
Here you can search all the U.S. Army's research about predicting performance through job analysis and specific content and situational testing.