Neck 4 times (twist each direction, then bend to each side)
Shoulders
Wrists
Fingers 3 times each (first knuckle near end of finger, then largest knuckle, then bend all fingers backwards, don't know which joint actually cracks there)
Thumbs twice
A good number of the vertebrae joints in my upper and lower back
Knees
Ankles
Toes
The midpoint of my foot (which is the equivalent bone to your thumb)
And yes I feel better after I do any of them. And no I don't think I've ever done every last one in a single sitting. And no I'm not afraid I'm going to get arthritis from cracking.
And of course RC5.