We live in a visual world, human beings are visual. Digital cameras are great fun to have photo shoots with and look at the end results right away. Your kid will learn more about their own expressions and learn to enjoy posing.
Using the excuse of "let's take a picture of you doing X", where X is the choir or activity your kid wouldn't like to do just when it is needed like brushing teeth, eating, dressing up etc. is a perfect con to get them excited about the activity you want them to!
You can never take too many awesome pictures of every day situations and look at them and discuss.