A vorarephile is someone who derives sexual gratification from the idea (for obviously this is not typically practiced in real life, at least not more than once by a given person) of being eaten or of eating other beings. The concept is not specific to FurryMUCK, nor even to furries in general (as can quickly be discovered by recourse to Google). Vorarephilia is sometimes called "voraphilia" or, most commonly, "vore." Those with this fetish are themselves called vores.
Different vores find different things erotic. Some prefer to be eaten whole; others like to be torn to pieces first. For some, the acts of eating and swallowing themselves are most appealing; others are excited by digestion, excretion, or the sheer idea of being fully inside another person or animal.
Vorarephilia contains many elements similar to domination and sadomasochism. To eat another is clearly a display of tremendous power, and being eaten is indicative of defeat and helplessness.