Many endurance athletes just can't bring themselves to drive to the gym three days a week after work to reap the benefits of strength training. However, there are ways to get the strength, flexibility, and injury prevention benefits of weight room workouts without the hassle of going to the gym.
If your goal is to improve as a runner, build lean muscle mass, and prevent injuries, you can accomplish this in the comfort of your own basement. With any bare bones, at-home workout program, the trick is to incorporate all of the appropriate muscle groups in as few exercises as possible. This means multi-joint, multi-muscle group exercises such as push-ups, chin-ups, dips, etc. Also, varying the angles, hand placements, and speeds will help to build more all-around strength, as opposed to strength gains in one specific motion/angle/speed/etc.
Upper body exercises that you should try and include are:
wide and narrow grip push-ups
wide and narrow grip pull-ups (palms facing towards you)
chin-ups (palms facing away from you)
dips (for your triceps and chest)
behind the head chin-ups (for your upper back/shoulders)
Even though you are running and exercising your leg muscles every time you go out for a jog, you should incorporate some lower body exercises as well, such as body weight squats and body weight lunges. These will help you avoid muscular imbalances sometimes associated with running and ultimately reduce your risk for injury.
Finally, don't forget to balance all of this activity out by including a core strength routine in your workout program a few times per week. Improving your stability, posture, and power transfer through greater core strength may make more difference in your performance, and your comfort while running, than anything else you do.