Amazon knows a thing or two about clouds. After all, besides being the biggest online retailer, with Amazon Elastic Compute Cloud (aka Amazon EC2), the company also provides the biggest public cloud service.
Cloud Drive isn't for IT departments. It's for you. It provides 5 GB of free storage, and you can use that storage to stream music to up to eight devices. And if you buy your music from Amazon, these tunes can be stored in Amazon Cloud Drive without using any of your allocated storage space. For the moment, Amazon is also offering limitless storage for music from other sources, but there's no telling how long this offer will last.
To both to upload and download music, you'll need to use the web-based Amazon Cloud Player. There's also an Amazon cloud player that's specific to Android devices.
If you want more storage, and if you intend on using Amazon to store your music collection you will, Amazon offers several tiers of storage, ranging from 20 to 1,000 GB at a price of $1.00 per gigabyte per month. So, for instance, 20 GB will run you $20.