Ice cave in the Skaftafell National Park in Iceland. Ice caves collapse and new ones form as each glacier grinds slowly towards the sea. Local guides can help you (without dying) find one. (Visit Skaftafell National Park in Iceland.
USA Road Trip Planner : Very cool website! It shows you all the roadside attractions (as well as food, hotels, etc) along your route! You can filter for whatever interests you. Will use it for the next road trip!