These days the logo of a game publisher or developer is a holy and sacred entity, never to be mocked or otherwise obscured. Back in the days of the Sega Genesis, however, Sega and its partners took great pleasure in constantly tweaking and modifying the SEGA logo that appeared when the Genesis was first turned on.
WhipAssGaming has a fascinating little gallery of the two dozen or so variations of the Sega logo, everything from the blood red logo of Chakan: The Forever Man to the rotating and scaling symbol of Sonic 3D Blast to Earthworm Jim flexing in front of the aforementioned emblem. There's four pages of nostalgia in the form of animated GIFs and Quicktime sound clips plus a fifth page of Sega 32X logos for good measure. Go ahead and do the Sega scream or sing the Sega jingle; you know it's what you want to do.