Pavonis Mons (Latin for Peacock Mountain) is the middle child of the Tharsis Montes, a range of massive extinct shield volcanoes on the planet Mars that includes Ascreus Mons and Arsia Mons. The better-known Olympus Mons, largest mountain in the known solar system, does not form part of this range.
In comparison to its brothers and sisters, Pavonis Mons is the runt of the litter, rising a mere 14km above the surface of Mars, as compared to 25km for Ascreus Mons and Olympus Mons. Much of its height is made up by the Tharsis Ridge itself, a huge geological feature encompassing approximately 25% of the Martian surface.
Pavonis Mons is topped by a simple caldera, as opposed to the complex caldera of Ascreus Mons - so either there was only one great eruption/subsidence event which created the mountain in its present state, or all evidence of previous collapses were eliminated by the most recent one. Like the other volcanoes of Mars, Pavonis Mons was created by slow, effusive basalt flows. Recent evidence suggests that along with the other Tharsis Montes, Pavonis may have occurred more recently than was previously suspected. Specifically, the very small number of impact craters visible in the caldera suggest that it formed far more recently than the 1 billion years previously hypothesized. Earth's own moon, Luna, gives an example of what a flat, geologically inactive surface should look like after hundreds of millions of years of bombardment by meteorites.
The Flaming Lips referred to this volcano on Yoshimi Battles The Pink Robots - track 11 is called Approaching Pavonis Mons By Balloon (Utopia Planitia). It's possible they did this out of pity for Pavonis Mons, which otherwise has little to distinguish it from its larger and more interesting siblings, but is, objectively speaking, a gigantic and extremely cool geological feature that would be remarkable on any other planet.
A picture of Pavonis Mons: http://www.lpi.usra.edu/publications/slidesets/mvolcan/images/volcanoesmars07.jpg