All the mentioned guides above are fantastic but they don't mention certain aspects of interviews. For example, some interviewers try to test whether you can handle the pressure. So purposely, they keep staring at their Blackberry or do other things while you are talking to see if it distracts you.
Also, they do ask some ridiculous questions to see if little things like that throw you off.
This is how I bombed my Morgan stanley interview back in Junior yr of college:
Morgan: Why shouldn't we hire you?
Correct answer: (per my friend who received offer) There aren't any reasons why you shouldn't hire me. In fact, if you don't make me an offer - you will miss out on a star banker of the future.
My Answer: uhhhh...what?
Then Morgan followed that question with this one right afterwards..
Morgan: Tell me one of the worst thing that you've done in your life.
Correct answer: (per my friend who received offer) Worst thing? What I did yesterday before this interview. I was considering one of your competitors, Goldman Sachs...
My answer: Ummm....I used to use Napster in highschool?
I can go on. But let me save my dignity by stopping here. The point is, regardless of what they ask, be confident and bold. Don't freak out...at least don't let them know.