This week's memory fact can be sung to the tune of "Dinah".
These videos previously posted are helpful for a 101 on volcanoes. Here's the extent of National Geographic videos on volcanoes I could find; I have not previewed them, and another great one from the BBC--pretty cool footage that allows you to see plate tectonics in action.
Older students might appreciate this Volcano World blog, complete with photos and videos. But their new blog through Oregon State includes virtual field trips to volcanoes, seven ways to build a model volcano including the intriguing trash-cano, and some volcano games, among a ton of interesting facts. There's also a semi-interesting video on the most recent Icelandic eruption back in March that grounded all of the planes in Europe, which mentions tectonic plates (the bottom video on the page is cooler, though). The top video requires reading, because it's soundless.