Any half baked graphics editing program could copy and paste a fake name onto a boarding pass.

The TSA and FBI have shut down sites in the past, like this one

http://www.dubfire.net/boarding_pass/

but he links to one they have never bothered to shut down

http://j0hn4d4m5.bravehost.com/

I have no clue if it still generates a legitimate boarding pass or not.

Over a year ago they said they were buying thousands of scanners to read encrypted boarding pass bar codes to prevent people from faking them.

In reality though, anybody going through all this trouble would just have a fake ID and a legitimate ticket. It's far less risky then drawing attention without an ID.