Solheimasandur Plane Wreck
Fjadrargljufur Canyon - any of these spots look familiar from the Justin Beiber "I'll Show you" vid? ;)
THE NORTHERN LIGHTS - one of the craziest, most surreal things I've seen!
Surfing - Amazing experience surfing in the snow! Go with Arctic Surfers!
If you end up going to Iceland I would recommend driving around the entire island! It took us about 19 hours, but we rented a rad van that had beds in it, and we camped every night in beautiful places away from any city lights-- prime for Northern lights watching!