It is hard to believe, but stretching is one of the most controversial subjects in exercise and sports.  Despite these disagreements, there is a developing consensus to
(1) never stretch "cold"muscles, 
(2) always take time to stretch after a run, and
(3) use a variety of exercises.

Here are some excellent  links (many with videos) to help you keep your body flexible, strong,  less injury-prone, and simply feeling better.