When I played Duke Nukem 3d, I heard some of the monsters in that game make a very familiar growling noise that I heard before. Upon loading Hexen, there was no question about it. Some of the monsters in Duke have the exact same sounds as some of the ones in Hexen!. These games were produced by two different companies (ID and 3D Realms), and they had two very different themes (one was in some medieval land, the other in not too distant future Los Angeles). I found this to be very amusing. ~_~
There are two Sega Mega Drive/Genesis games that share all of the same sound effects: Comix Zone and Sonic Spinball.
The Cave of Wonders in Aladdin and Malebolgia in Spawn have the same voice (Frank Welker using his famous "Dr. Claw" voice).
I have a friend who has a cell phone that makes a sound effect that was also used in Sonic 3(?) when flipped open