Some examples of inside voxels on my current adventure:
Trashcans with trash inside
Refriderator with food inside
Couch with cotton insides (looks awesome when shot!)
Suitcase with clothes inside
cabinets with pots and pans inside
etc...all this stuff looks really cool when destroyed.
Also, anyone seen the City map?  They created each individual floor with stairs and elevators connecting them.  That made destroying them SO satisfying!