Pu’u O’o: What it looked like just before it collapsed. See also this USGS timelapse movie of Pu’u O’o’s crater lava lake from March 20-April 18, and a blog post with a few good flyover photos on April 29.
(Pu’u O’o is a large vent on Kilauea’s shoulder that’s been erupting since 1983. See USGS / HVO photo history of the Pu’u O’o eruption.)