Mount Erebus was named after one of the first ships to come near it. The name is quite appropriate because its namesake is the embodiment of darkness as described in Hesiod's Theogony. Erebos was the sibling of Nyx and the offspring of Chaos. In later mythology Erebus is described as the land of Hades itself where the dead reside.
Given the location of Mount Erebus (77°32'S, 167°10'E), there's little doubt as to why that moniker is so apt. Located in Antarctica - the dreariest landscape on the planet (with the possible exception of the Utah Salt Flats) - Mt. Erebus is the southernmost active volcano in the world. It was discovered by James Clark Ross in 1841, for whom Ross Island is named, where Mt. Erebus sits. Overlooking McMurdo Sound, Mt. Erebus shares the island three extinct volcanos: Mount Bird, Mount Terror and the Hut Point Peninsula, the last being the home of McMurdo Station, the main United States headquarters in Antarctica. Erebus reaches up to an elevation of 12,500 feet (3800 meters).
Erebus is a stratovolcano, meaning that it is a volcano with alternating layers of earth and ash. The volcano was built over the last million years (or so) by its frequent strombolian eruptions intersperced less frequent ashy eruptions. It has been continuously active since 1972, and contains a alkalic lava lake - one of the very few lava lakes in the world.
The temperature around Erebus is typically around the -80º Fahrenheit (-60º C) mark in the winter and during the summer it burns under the blistering sun at a whopping 0ºF (-18º C).
Mt. Erebus is also the sixth map of the third episode in the original Doom. (Editorial: It's one of my favorite levels in the game.)