What exercises will help relieve knee pain?

Strengthen. quadriceps muscles and tape your kneecap based on the direction it goes when your walk or run. This can be accomplished by seeing a sports training physical therapy program.
Quad strengthening. Almost all injuries about the knee benefit from quadriceps strengthening exercises. Simple straight leg raises, mini squats, walking, treadmill and stationary bike use, and an elliptical trainer can all help to decrease knee pain. The best advice is to discuss the etiology of your knee pain with your physician before beginning an exercise program.
Depends on problem. There are many good exercises for knee problems but you need a diagnosis to tell you the correct ones. See your orthopedic surgeon and get a diagnosis and then this guides your exercise routine.