Keep your answer to one or two minutes; don't ramble. Use your resume summary as a base to start.
What do you know about our company?
Do your homework before the interview! Spend some time online or at the library researching the company. Find out as much as you can, including products, size, income, reputation, image, management talent, people, skills, history and philosophy. Project an informed interest; let the interviewer tell you about the company.
Why do you want to work for us?
Don't talk about what you want; first, talk about their needs: You would like to be part of a specific company project; you would like to solve a company problem; you can make a definite contribution to specific company goals.
What would you do for us? What can you do for us that someone else can't?
Relate past experiences that show you've had success in solving previous employer problem(s) that may be similar to those of the prospective employer.
What about the job offered do you find the most attractive? Least attractive?
List three or more attractive factors and only one minor unattractive factor.
Why should we hire you?
Because of your knowledge, experience, abilities and skills.
What do you look for in a job?
An opportunity to use your skills, to perform and be recognized.
Please give me your definition of a .... (the position for which you are being interviewed).
Keep it brief -- give an actions- and results-oriented definition.
How long would it take you to make a meaningful contribution to our firm?
Not long at all -- you expect only a brief period of adjustment to the learning curve.
How long would you stay with us?
As long as we both feel I'm contributing, achieving, growing, etc.