Here are some more additions to The Best Sites For Learning About The Volcano In Iceland:
Ashes to Airlines: Examining the Effects of a Volcanic Eruption on Our Global Community is a good lesson plan from The New York Times Learning Network. It would need to be modified for ELL’s, but there are some useful ideas there.
The Los Angeles Times has a special page filled with multimedia resources on the volcano.
MSNBC has several multimedia resources on this page.