What's worked great for me in the past is going into the interview with a prepared list of questions, typed with enough space between questions to write in some notes. An interview is a two-way thing. You want the job, they want an employee. It's not just about them drilling you with questions, you want to make sure they are right for you also. It portrays to the interviewer that you are serious about the job and you are demonstrating to them they better be prepared to offer a good position, salary, benefits, etc. if they are to satisfy you. Sounds cocky, I know, but it is effective. Some of the questions I use to ask (not in order) were:

1) Why are you hiring for this position? Is it a new position? If you are filling a vacancy why is the job vacant?
2) Aside from employment, what can your company offer me? Do you have education-reimbursment plans, benefits, etc.
3) How is business? Is the company doing well financially? Are sales strong (if applicable)? You may want to research this first and be able to contribute to the answer given as well pose specific questions. For example, you are going for a job at Ford you may ask, I know Ford has been experiencing a decline in sales over the past few years but I'm also aware the new CEO is expected to shake things up and with all the research Ford has put into hybrid vehicles do you expect a strong and stable company to emerge in the next few years?
4) I love this one; it makes the interviewer squirm...Why should I work for you instead of your competitor? Do you offer a better compensation package, have a better work atmosphere, what makes your company the best place to work?

Anyways I could go on forever. My last interview took me 2 hours to get through my list of questions and when we were finally done I apologized for dominating the conversation. The two interviewers said it was the best interview they ever conducted and offered me the job on the spot. I went on to work there for 2.5 years before I opened my own business. I've used this technique in the last 4 job interviews I've had over the past 10 years and I got the job each time.

Thanks for the tips Rob!

This technique seems to be very effective although some people are afraid of using it thinking if they ask these sorts of questions they may lose the job. On the contrary- This shows the employer you won't take just any job offer, you did some research, and instead of them interviewing you are interviewing them! ;)