These links will allow students to take virtual field trips
http://www.field-trips.org/sci/volcano/index.htm- This site has trip to places like Deserts (Gr. 5-12),Dinosaurs (Gr. 2-5),Endangered Species ,Fierce Creatures (Gr. 3-7),Hurricanes (Gr.7-12),Natural Wonders (all ages),Oceans.
http://www.uen.org/utahlink/tours/fieldtrips2.cgi?core_area_id=3- I like this site because the trips have important questions that might be asked and then answered.
http://www.sciencecompanion.com/samples/virtual-field-trips-from-science-companion/- This site is nice because it list age ranges before the trips.
http://www.kn.pacbell.com/wired/fil/pages/listvirtualgr.html#cat2- This site also takes the studnets on a field trip but has a much shorter list.
http://adventure.nationalgeographic.com/adventure/- I am listing the site because you can find a ton of wonderful trips to explore, and they post new information all the time.