Greek Seas Operate twelve sailing yachts crewed from Athens, with special rates for students. Includes boat listings, itineraries, trip planning service and blog. http://greekseas.com/
Islands.com From Bora Bora to the Caribbean, Tahiti to Hawaii, an online guide to islands of the world. Includes photos, maps and things to do. http://www.islands.com
Guide for travellers interested in staying somewhere truly different. Includes underground hotels, undersea lodges, tree houses and igloos. Can be searched by type of lodging, location, or "outrageous" rating level.