What are some good low impact exercises with arthritis?

Swimming. Swimming is a great exercise for people with arthritis. Make sure to check with your doctor before starting an exercise program to make sure it is safe for you.
Low impact exercise. This is an excellent question! There is evidence that Tai Chi practice improves pain, joint function and there are benefits beyond the skeletal system. How about better sleep, more energy, better coping skills ( we call that self-efficacy). Try it on you-tube. The Arthritis Foundation also has a Tai Chi program. Have fun!
Add some others. Bicycling, rowing, kayaking, paddeling. Resistance exercise with higher reps d lower resistance.