Why would Monster Worldwide be calling me?

So, I go up the street to the store for a few minutes tonight, and I came back and saw I had someone call my phone while I was out on the caller ID. It says Monster Worldwide. So, I look it up on Google and find out they are Monster.com. I am in college studying web development and I am in the process of starting my own web business, but I really don't know where they may have gotten any information about me. My resume is floating around, of course, but my web site for my business is posted as under construction. Do they solicit businesses to use their site to find employees by phone? I don't think they do. Any suggestions as to why they may have called? I tried calling the number back but it just goes to a dial tone after dialing the number. I just want to know what motivated the call before they call back. Anyone else ever have them call?