All the photos here.
We took a guided day trip from Quito to the nearby national park around the Cotopaxi volcano. The tour company drove us and a few others out to the park, where we would stop below the volcano, at the park's very small museum, and finally, part way up the volcano. From about 3900 m, we would begin a 2 hour walk up to the edge of the glacier at about 5000 m (16,400 ft)... this is probably the highest altitude we've ever hiked to! There is a hut/refuge about half way up the trail to the glacier, where you can get outfitted to do the actual ice climbing to the summit after the sun goes down. We stopped here for lunch on the way down, but the food was bad and there wasn't enough for vegetarians. After lunch, we walked back to the bus and took an 11 km (almost 7 mile) mountain bike ride down the volcano to a lagoon near the park entrance. We also saw an Andean wolf (which is really a fox) and milked a cow! All in all, a very fun tour.
Interesting after story: On another day, we ran in to a woman who recently quit from the tour company we used to go to Cotopaxi. She complained that they underpaid their guides, skimped on food, and treated her terribly. So.... for those of you looking for a particular tour company to use if for Cotopaxi, we can't really recommend one, even though we had a good trip with ours.