I applied to nine summer internship programs all with varying hear by dates between the end of February and the end of March. One of the programs just sent me an email of acceptance into their program yesterday but gave me less than a week to respond with my decision. I would really like to here back from all of the programs before committing, especially since this was not my top choice. Does anyone have any advice on what I should do? I have asked around and my friends suggested I could ask for a short extension, like one to two weeks, and email the other programs to inquire about my status.
It would be helpful to know more about you … e.g.,. are you an MBA student or an 8th grader? 
It would also be helpful to know more about the internships you’re seeking (in what field, how competitive, etc.) So feel free to send that information to “Ask the Dean,” if you want a new and improved reply: https://www.collegeconfidential.com/editorial/contact-us
I agree with your friends that you should ask for an extension, but FIRST contact the other programs (at least your top few choices) and explain that you’ve been accepted elsewhere and a reply is expected immediately. Also explain that THIS internship (the program you’re contacting) is a top choice, so you don’t want to accept the other if you’re in the running for this preferred spot, but that you also don’t want to miss out on a good opportunity by waiting to notify the organization that has accepted you. Politely point out that you are hoping you could get an idea of when you’ll be hearing before you respond to the current offer.
Do NOT, however, send this query to any program that has clearly already told you when you’ll hear. You don’t want to appear as if you expect special favors.
Once you have an idea of when you might be notified by your other programs, you can contact the one that already wants you and ask for an extension that is long enough to allow you to hear from at least a couple of your other more favored choices.
If you’re told that you can’t have an extension—or at least not an adequate one–you will find yourself in a bind that most of us encounter periodically throughout life … the classic bird in hand versus two in the bush situation. You will have to ask yourself if you want to jump on this sure-thing offer or wait for something better to come along (although it might not). It could be a tough decision, but it will be good practice for future dilemmas which may even carry weightier consequences.