Here is a great example of density altitude and the negative effects on a light plane. This 4 seat Stinson 108 went splat into the trees when the pilot just couldn’t climb. Unfortunately, he had a few chances to stop the take-off roll. Luckily no one was killed. Great video by AvWeb explaining how density altitude effects aircraft performance. Excellent example!
http://www.youtube.com/watch?v=OVM3RRd1vf0&feature=share&list=ULOVM3RRd1vf0