Amazon has taken a big step and beaten both Apple and Google to the punch with their new Cloud Player service. Users will be able up upload music to their free 5GB Cloud Drive, and stream it to most web browsers and Android devices. There is also a tie-in with music purchased from Amazon's MP3 store, which can be loaded directly into the Cloud Drive.
There are a few things of note here. The 5GB of free space for all users is enough for some people, but if you intend to upload all your MP3s, 5GB likely won't cut it. Amazon will sell you additional storage for a reasonable price. Should you buy an album from them, you can get a free 1 year upgrade to 20GB of storage. It is also interesting that Amazon is opening this service up without licensing deals from the labels. They may not need them, but that wouldn't stop the labels from making a stink over it.
Android users can update their Amazon MP3 app, which now includes the Cloud Player software. Users of iOS are currently out of luck as even the Safari browser does not work with the service. Have you given Amazon's Cloud Player a shot?