I was over at Tanya's reading a small nugget about the various IDs she carries and how some could be forged easier than others when I started thinking a bit...
Jenn and I just recently went to go get passports. Now, in the US, for a new passport application you need to bring your driver's license and your birth certificate. To get a driver's license, you need three documents: one "proof of age" and two "proof of identity." At least, that's how it is in Oregon.
The proof of age for your license can be your birth certificate. This can double as one of the proof of identity documents. The other proof of identity could be a company ID card, a medical card, or some other such thing.
The company ID, medical card, or other proof of ID could very easily be forged. I could whip something up on my printer in about 10 minutes for that. Basically, the only thing stopping you would be the birth certificate. They're printed on special paper so you really can't just forge one up.
Fortunately (or unfortunately?), Jenn had somewhere along the lines lost her birth certificate, so she had to go in to get a new one. \$15 and a few minutes later, she had a brand-spanking-new one. No one checked any ID or anything on her; she just had to know things like her mom's maiden name and a couple of other things that could pretty easily be obtained by anyone who really exerted the least bit of effort.
Then I started thinking about movies where you see these people going through all this trouble to have passports made and things, and I was thinking, you know, you could get a fake passport a whole lot easier if you actually went through the legal channels. Nobody questions anything, and a few weeks later it gets mailed to your house. One would think there would be more of a background check or something prior to issuing a new birth certificate, but apparently not. Makes you wonder, doesn't it?