Stretching after every workout is a must for me, and should be for everyone. You will be more limber, which will help you run better. Also, you will have less soreness in your muscles if you give them a nice slow stretch after you run. I am one of those unfortunate people who is incredibly non-flexible. When I try to touch my toes I can reach just about halfway down my shins...on a good day. Slowly but surely I get a little more flexible every day, but it never gets to the point where I can touch my toes. Mostly I have been doing my old high school track & field stretching with a few other stretches added to cover all of the muscle groups. I may try added some yoga.
You should also be doing some cross training. My bike is out of commission at the moment or I would be riding. I add in some light weight lifting to increase my core strength and to strengthen my back - which is of major concern for me. Sometimes I just turn on loud music and dance around like a crazy woman for a half hour to an hour. The dogs and my cat run and hide, but it's something I have always loved to do.