The existence of a low end instance in addition to some higher end instance availablity options is pretty awesome, this makes it cheap enough for something which you might only really need VPS level availability to make sense to build on top of their platform and then if you need a bunch of instances all at once ok to fire up. They have quotes on the site like "I couldn't even find Amazon's phone number" which seem a bit miss-leading (Amazon simply charges for phone support), but yay for competition :)