M.E. Lad has eaten his way out of at least one cage. He is also one of the few characters possessing this ability to demonstrate the logical but downplayed corollary power of Acid Spit. Think of the "Alien" movies and their 'molecular acid for blood', but a controllable projectile.
He can eat laser beams, on the grounds that energy is also a form of matter.
He's also eaten an explosive device nobody could destroy, remove, or molecularly alter. People were reminded why they kept him around: as a plot device.
Ditto for Upchuck the alien "Gourmand" of Ben 10's transformations.
...Only he can't eat anything that's edible to regular humans.
Ditto again for Masu in Deadman Wonderland (although this hasn't been shown as a power per say).
In Phil Foglio's adaptation of the Myth Adventures series, dimensional-castaway and powerless-magic-instructor Aahz will occasionally snack on various nearby objects, which have included a goblet and a doormat. The behavior was not specifically mentioned in the source novels. However, the cuisine from Aahz's home dimension of Perv (making him a P-e-r-V-E-C-T, thank you very much) is as disgusting to the reader's sensibilities as Asprin could make it, which may mean that Foglio's visual joke is a Justified Trope. However, as Aahz is only depicted doing this during long segments of exposition, it may simply be Foglio poking fun at Asprin's writing depicting Aahz chewing the scenery.
Also his daughter Gali/Galacta; she lives on Earth, tries to let the locals in peace, and eats alien invaders and bioweapons. It takes all her willpower to NOT eat the yummy Earth. And it has gotten even worse since she became pregnant.
If you consider that Galactus eats everything on the planet, he's got a pretty big range, too (although he probably processes those things along the same lines as we would with seasonings). He just does it in fewer bites.
Concrete can eat rocks, wood, cotton, just about anything he wants to.