Mad genius designer Keita Takahashi left the series years ago, but Katamari is still among my favorite game franchises of all time (and I'm not alone), and it's a natural fit for the iPhone's tilt-controls.
After rushing out a release that wasn't quite ready for prime time (read: huge slowdowns and not the most responsive controls), a quick update has gotten this app where it needs to be, giving you the satisfaction of motion-controlled rolling form the privacy of your own toilet.
Lite version Free, Full version $8
From The App Developers: The King of All Cosmos has accidentally knocked all the stars out of the sky during a crazy night out. It is up to the pint-sized Prince to put the twinkle back in the heavens in I Love Katamari. I Love Katamari delivers an experience only possible on the iPhone/iPod touch.