Hairy-tailed mole, Parascalops breweri
Star-nosed mole, Condylura cirstata
Eastern mole, Scalopus aquaticus

Size: Depending on the species, 1–5 ounces.
Hairy-tailed and Star-nosed moles are about 5–5 1/2″ long, including the short tail
Eastern mole is about 3 1/4–8 3/4″ long.
Snout of a star-nosed mole is ringed with 22 small, pink, fleshy projections that make it look like it has a sea anemone on the tip of its nose.

Signs of their presence:
Tunnels, or “runs,” in the soil or lawn. (Runs of star-nosed moles are usually deeper and less noticeable than those of hairy-tailed moles, except, at times to be short and very crooked, because if a mole finds an area that’s full of food, it tends to dig all around, feeding. They’ll abandon these runs when there’s not much food left in them. Dead grass over the run is usually a sign of an old, abandoned run. (Moles don’t eat grass, but they may loosen the roots from the soil, which can kill it). Their travel tunnels are usually long and straight and often follow an edge, such as a driveway, fence, or foundation. Look for travel tunnels that continue into wooded areas because these will be the best spots in which to set traps., in well-watered golf courses.) These tunnels are seen most often in the spring and fall, when the soil is moist, soft, and easy to dig. Moles make two kinds: feeder and travel tunnels. Feeder runs look like a long, squiggly, rounded ridge that’s about two inches wide.
Molehills (also called boils or mounds): small, cone-shaped piles of soil that are usually just a few inches high and anywhere from a few inches to a foot wide. They vary in size. Often seen in the late fall, as the moles prepare for winter by digging deeper tunnels that are under the frost line. At that depth, the moles can’t toss up the soil as they go, which is what they do when they’re near the surface. So they’ll usually dig forward for a while, then stop, and carry the soil up to the surface where they dump it, creating the molehill. Moles also dig deep tunnels in the summer when the soil is dry. Then, they’re following the earthworms, one of their favorite foods.

It’s unlikely you’ll see or hear moles, or find scat or tracks because they spend their time underground. Although they feed and travel in the shallow, surface tunnels described above, they find shelter and raise their young in deeper tunnels that could be 6-24″ below ground.

Common nuisance situations:

Time of year: Spring (April–May) and fall (September–November), when surface soil is moist and easy to dig, and grubs and worms are nearest the surface
Tunnels disfigure lawns and can wreak havoc in a garden.

Disease risks: almost none.
For more information:
http://www.nwco.net/08-AppendixBNuisanceSpecies/8-06-Moles.asp