This is a tough one, and you have to have a good read of your interviewer(s) to be able to frame this question in a way that will have the intended effect. Let's start off at the post-interview section, which is where this question would typically be asked.
First of all, I strongly recommend having at least 1 or 2 questions to ask at the end of the interview. If there are multiple interviewers, try to sprinkle the questions around. This can give you an idea of which interviewers like to talk, and about what. Try to keep your questions related to your position and how you'd be working with your interviewers.
How closely would I be working alongside/under you?
What kind of proprietary technologies do you use?
This combines the presumptive approach often used in sales ("Do you want this in black or blue?" instead of "Do you want to buy this?") and actually demonstrates in interest in something beyond the girth of their compensation package. Modify these to fit the position/company/interviewer as you see fit.
Secondly, give yourself a backdoor back into your questions that you asked previously with the following:
Are there any questions you asked where I didn't get around to answering them directly and fully?
It's an interview. We all get nervous, we ramble, and we inadvertently frame questions incorrectly and answer something they didn't ask. Sometimes, it doesn't really matter and they get the information they wanted - albeit in a roundabout fashion. But sometimes, they asked what 2+2 was, and we go off on a tangent about all the cool things we've done using addition but never got around to saying "4."
Finally, after having used the interview up to this point to get a read on your interviewer(s), decide on how formal your next statement needs to be. On a sliding scale of super-casual to super-formal, I have used the following:
How'd I do? Told you I was a super genius.
I had a great time meeting with you (all) today. I have a really great idea of the kinds of things I'll be doing here, and I'm excited to put my skills to work for you.
Thank you so much for your time in offering me an interview. I'd like to clearly state my enthusiasm and interest in becoming part of your team.
The second one is probably the safest bet, because it walks the line between show (emotional enthusiasm, may be construed as unprofessionalism) and tell (flat affect, may be construed as insincere in a smaller environment. Regardless of which you choose, make sure you clearly state your interest and try to nail down when you can expect to hear from them.