Have you signed up for Amazon Cloud? It's a newly launched service that offers 5 GB of free online cloud storage, and affordable paid plans up to 1 TB. Competing with DropBox, Amazon Cloud takes measures one step further -- integrating with its online store to provide over-the-air media access, like SugarSync, Mougg, and AudioBox.
Unlike those latter services, however, Amazon Cloud provides media storage for free -- so long as you purchase that media from the Amazon store. Your Amazon music will not eat away at the free 5 GB