I recall a version that was an ascii string that you could save as a file with a .zip extension and it would unzip into the source.
> This gif file contributed by Robert de Bath, contains a surprise inside. Mr. Bath writes: "There are two tiny facts about GIF files and ZIP files you might like to know about: GIF files have their length defined at the start of the file; any bytes after are ignored. ZIP files have a table at the end; anything at the start of the file is ignored. The result is that a file can be both a GIF and a ZIP, just change the extension."
I also like the gallery, which contains a variety of code-golf like discussions of the edge cases of US 1st ammendment protections.
Though, it wasn't 1/100th as ugly as this block of graffiti spam.