Marvel Comics has teamed up with CafePress to offer free(ish) S.H.I.E.L.D. ID badges.
Granted, the official Agents of S.H.I.E.L.D. website offered something similar, but that was just a digital file - this is a real, honest-to-goodness physical ID badge. Impress your friends! Intimidate your enemies! Earn the pity of your non-nerdy family members!
Now, it's not "free" free: you have to pay $1.25 in shipping (and any applicable taxes), but that's fair. They're sending you a real item! So just go to the site, upload a photo and fill out your information!