I once edited the OS 9.2.2 startup screen (via ResEdit, of course) to look like System 7.5.0 (the version immediately before the one where the now familiar Mac OS screen was introduced). It was quite neat, I thought, and it took a lot of trial and error, since I had to get it in just the right spot for it to look right.

I probably still have that modified System file floating around here somewhere....

c