This video has been posted all over the place now, but I just can't not post this here. The Sega logo at the start of every Mega Drive game was possibly one of the main reasons the Sega brand became so well known. You ask any casual gamer who was raised in the 16-bit era, and they'll likely tell you they used to have "a Sega" rather than "a Mega Drive". Well this video has 143 different game intros of the Sega logo, even some from the Mega CD, 32X and Game Gear.
Almost all of them do something unique with it, ranging from tech demo like special effects to the game's main star interacting with it (with the best example being Vectorman, which actually let you control the character, jumping and shooting at it for as long as you please) and even some unique screams of the brand name (such as the Jurassic Park one with a T-Rex growling 'SEGUUUAHH!"). Some games even had more than one that would play at random each time you switch on the system (For example: Eternal Champions and Bonkers). These didn't just come from Sega's own games either, as all the third parties joined in on the trend too, giving the Mega Drive versions of multi format games something unique over the Super Nintendo or Amiga versions. This was in the days before consoles would have their own specific logo which would play every time you turn on the system. It's a real shame this individuality was lost to slapping a flat logo that sits on the screen for a few seconds with all the copyright details. Enjoy this wonderful display of what made Sega special in the early 90's.
Oh, and just in case there's a game within the video that you can't quite name, InfiniteContinues, the creator of the video has posted a entire list of the games featured.
P.S: There is also a website called Whip Ass Gaming who did a whole collection of animated GIFs of the Sega logos(many with the sounds too) which can be viewed HERE. Funnily enough both are called "The Sega Logo Project". How great (Sega Fanboy) minds think alike =)