The original Macintosh team’s signatures are engraved in the plastic of the original Macintosh’s case. The idea was that since the original Macintosh was art (according to Steve Jobs) and artists sign their work, the original Macintosh team should sign theirs. So they did. The signatures are inside the case, seen by very few people… but they are there.
You can read all about it at Foklore.org. Warning: you can lose an entire morning on that site. It’s that much fun.