Some young savers stash their cash in shoe boxes or jelly jars. Others use "piggy banks," which today look more like spaceships or cartoon characters.In any case, the same problem arises. Sooner or later, the piggy bank or jelly jar fills up, and you have to make a decision: Should I spend the money or continue to save? And if I continue to save, should I open a bank account or just find a bigger jar?Maybe you've had to face such a decision yourself...