Scratch

Okay, I'll start with Scribblenauts. I'll help you guys a little with some cool things to spawn and what they do.
Cthulhu- A green, tentacaled thing with wings. They're my creature-of-choice.
5th Cell- The 5th Cell logo.
Jeremiah- The creator of the game, Jeremiah Slazka. He breakdances!
Rick Roll- The internat guy that sings "Never Gonna Give You Up", Rick Astley. He dances around, then explodes.
Teleporter- Go up to it and tap 'Ride.' It brings you to the 5th Cell HQ where there's the logo, a computer, some developers, a car, and Liz, the zombie girl.
Time Machine- Ride this to go to either prehistoric times, medievel times, or into the future.
Wormhole (Intergalactic)- After a few seconds, randomly spawns a dangerous creature.
Da Man- Spawns a giant copy of the Scribblenauts game card
Zombie Repellant- When holding, repels all zombies you get near.
X-Ray Vision Goggles or Night Goggles- Enables different views on the world.

By the way: Lv. 8-11 in Frontier is a Back to the Future reference. It has the scientist standing on the courthouse with electric lines attached to the tree. The clue is "Get the Charge at 88" 88 mph isthe speed the Delorian has to get to to time travel. You have to bust the power lines to get the Starite.

Also, Lv. 9-7 in Dark Hollow is Bioshock reference. It has a Big Daddy (a giant with a diving helmet) and a Little Sister (a little girl.) Plus, the underwater city lookes like Rapture.