can anyone who is computer savvy help me please

My roomates and I all have iTunes, and frequently their music shows up on my computer through our shared internet connection. I know that there is a program in existence that would allow me to not only listen to their music, but actually pull the music from their computer and allow me to put it on my own. I think Jav is the one who originally told me about this. Could anyone tell me what this program is called and where I can get it for free? This would be amazing...thanks.