As blake said, these programs are quines. The most amazing quine (actually a viral, self-replicating quine) is Damian Conway's SelfGOL program- designed to win every category of the obsfucated perl contest some years back. He occasionally gives lectures explaining the monstrosity.
In addition to being a quine that can make other programs into quines, it's a scrolling marquee and a game of life.
It's also a great example of the nooks and crannies of perl.
Unfortunately, I don't know that he has released the program for general consumption.
Sorry, I'm a little off-topic, but it really is an amazing program and the SelfGOL lecture was the highlight of the conference for me last year.

-pete
Entropy is not what is used to be.