Fifteen years ago, "quantum computing" was virtually unheard of. In 2006, it has an APS topical group to itself, and gets hundreds of millions of dollars in funding per year. Why all the excitement? I'll explain the three fundamental reasons why quantum computing is exciting — (1) quantum computers can solve certain problems amazingly fast; (2) what we learn about quantum computing should lead to new technologies; (3) we think we're understanding the universe better. In particular, I'll focus on the problems that a quantum computer could solve. There are only a few, but they're important, and the advantage over a classical computer is stunning. I'll take a stab at where this power comes from, and try to debunk some of the more common myths about quantum computers.