CZARS?

What is all this "czar" business?

Obama appoints a car czar, an education czar, a pay czar, and other czars.  Who are these people?  What are their functions?  What powers do they have?  Who has any oversight over them other than Obama?  Where are the checks and balances?

This all sounds too ominous to me.  Russia had czars.  Why do we need czars?