Macintosh ROMs (any of them) 

With a debugger, look at the last few locations on the ROM of your machine.

Developers put their initials there, as well as the date that the ROM was linked.  For example, the 128k ROM (Mac Plus) contains, at $41FFC0- $41FFFF: ALR ELR BA BMB EHB JTC SC DLD PWD KWK LAK SEL BWed, Nov 6, 1985 which are the initials of ?, Erich Ringewald, Bill Atkinson, Bill Bruffey, Ernie Beernik (sp?), Jerome Coonan, Steve Capps, Donn Denmann, Pat Dirks, ?, Larry Kenyon, and ?. (Contributed by Scott Lindhurst and Ed Tecot)