Amazon Cloud Drive goes unlimited: $59.99/year for everything

https://www.amazon.com/clouddrive

There is a caveat. File can't be larger than 2GB.

http://www.amazon.com/gp/help/customer/display.html/?nodeId=201376540&ref_=cd_tou_fp&ref_=cd_pricing_tou

3.2 Usage Restrictions and Limits. The Service is offered in the United States. We may restrict access from other locations. There may be limits on the types of content you can store and share using the Service, such as file types we don't support, and on the number or type of devices you can use to access the Service. We may impose other restrictions on use of the Service.