Well Cami, I have never made a Futurama shirt myself, but I am planning on making one soon, so I've done a little reserach.
So here is a link to an old thread in which Paul at FSAC discusses how he makes his. It's simpler than you think! http://www.peelified.com/cgi-bin/Futurama/15-000199-1/
To quote him:
"T-Shirt transfer paper, printer and iron."
To get more detailed instructions, it may be a good idea to open another thread asking for the best way to make your own Futurama shirt. I'm pretty sure you wouldn't be the only person to benefit from it!