It doesn't happen often, but when the cloud goes down it sure is a big deal. Whether it's a Web outage that restricts access to data or a server that goes kaput rendering services useless, cloud outages can hurt. And as we start to rely more and more on the Web to conduct business, outages can be even more severe. So far this year, there have been some high-profile cloud outages that raised the ire of users and prompted questions around the trustworthiness of the Web for housing applications and essential data. Here we take a look at 10 big ones that rocked the cloud world.