One of the five technological devices I think is very useful is mobile phones. I always carry it on because I'm afraid to be in a situation I can't resolve by myself and don't get help.
Satellite dish are very usefull because allow to receive images and sounds from any place through all the world
Laptop computers are very useful and nowadays they are essentials for scientist, politics and so on
Microwave oven is also very useful but I think it's not essential. It helps doing your life easier but you can live without one of them
Memory card is essential for many kind of people as students, scientists, travellers, politics, business men, etc.