The perfect example. Mr/s Companion Cube literally does nothing, yet managed to ensare the attention of gamers with ease. Sure it helps that it's a key part of 2007's best game. Yes we're commanded to care for it by the ominous GlaDOS. But we didn't need to be ordered to love it - we simply did. Maybe it's the subtle heart decals, we aren’t sure, but something about it made everyone go nuts. See:

A gingerbread creation from gamecakes.com.

A plush cube selling for $365, as noted by Kotaku.

A massive cube auctioned for charity, eventually selling for $1,200.

This early adopter branded their ambiguous legs with both the cube and its counterpart, the cake of lies, as submitted to the aforementioned Kotaku.

Even Halloween was overtaken by Portal/Companion Cube love, as seen on Joystiq.

Bottom line - everyone loves Portal, and that means everyone loves the cube. But there was one item we just couldn't deny, and it had to take the number one spot. Chances are you'll agree...

So meaty: While we're on the subject of cubes, Unreal's meat cube managed to bring the GR offices to a halt when it first popped on the intertubes. All it does is flop around and absorb damage, but it's the primary reason we're eager for Gears 2.