I love cracking my elbows, ankles, toes and wrists too- along with my knees, hips, neck, back and fingers! Feels sooooooo good! Especially when the chiropractor does it, 1000000X's better! :P
Yes, knees are fun too, but I can't do them that often. Have never cracked my neck or back...but crack my fingers all the time! Including the thumb!