Mexico City, Mexico
One of Mexico's largest and most active volcanoes had a large eruption yesterday, 11/20/2011, as its lava dome failed allowing ash, gas, and magma to blow out of its top, resulting in an ash plume approximately 3 miles high. The volcano is typically not a danger to anyone, and rare ash fall in populated places is typically not a nuisance. Nonetheless, authorities have places a 12km exclusion zone around the volcano as a precaution.
The below photo from the AP shows the towering ash column over Mexico City.
Popocatepetl (or Popo) has been erupting intermittently since December 1994, and is a good tourist attraction for Mexico, although unlike Hawaii's volcanoes, it's a bit more dangerous to get to the summit of this stratovolcano due to its sometimes explosive nature. However, as you can see, it makes for a beautiful backdrop in the distance to Mexico City.
Popo has had several major plinian eruptions, the most recent of which occurred at about 800 A.D. This resulted in pyroclastic flows, lahars, and ash fall. It is probable that Popo will have a similar episode in the very distant future. For now, it's one of those volcanoes that is simply fun to watch.