#4 Return of the Space Hamster
If you purchased a pet space hamster from the Citadel gift shop in Mass Effect 2, you can actually get him back again in Mass Effect 3. Just head down to the Normandy's engineering deck, then go down the stairs to where Jack slept in the second game.
Listen for a squeak. When you hear it, look down. If you're quick enough, you can catch your space hamster as he scurries across the ground. After that, he'll be in your cabin, right where he was in the last game. It's just a shame that he doesn't count as a War Asset.
