I get calluses and my husband uses his dremel to take them off. He's very, very cautious and just barely brushes the callus with the dremel, but you can tell it's working by seeing the dust fly. Well, I guess it would actually be skin, not dust, minute, dust-sized flakes of skin. I guess that's not accurate either. Okay, minute, dust-sized flakes of callus. Well, I imagine you know what I mean.
Anyway, I can tell when he's getting close to good skin because it feels hot. I usually yell or scream at that point to let him know he needs to stop. :D
He's also been known to use his sharp pocketknife to trim calluses off, but the dremel is probably safer as long as it's used carefully.
The podiatrist I go to once in a while also uses a dremel for calluses. I think my DH does just as good a job and it saves the expense of an office call.
He's pretty handy when it comes to ingrown toenails, too.
By the way, none of the above applies if it's a plantar's wart. :D