Mt ASO on Kyushu Island, Japan is one of the largest calderas in the world… by williamcho on Flickr.
Volcanoes Big Island, Hawaii by Weiguo Jiang on Flickr.
zen-droid:

Methane Moon by Bruce Omori
Stromboli (IMG_7046) by Etnastürmer on Flickr.
Ash cloud from May 18, 1980 eruption of Mount St. Helens over Ephrata, Washington (230 km (145 mi) downwind).