Source: http://lifehacker.com/#!5790017/scrobble-tracks-to-lastfm-from-amazon-cloud-player-with-a-userscript
Last.fm is one of our favorite music recommendation and statistics engines, and if you've fallen in love with Amazon's new Cloud Player service, you're probably looking for a way to scrobble the songs you listen to. This script will do the trick.
Last.fm is pretty powerful, but only really works well if you keep scrobbling what you listen to. The more you scrobble, the more accurate your recommendations will be. To make sure your Last.fm account keeps up with your cloud listening habits, just install this userscript into Chrome, Firefox with Greasemonkey, or your other favorite compatible browser. Then reload Cloud Player, and you'll notice a Last.fm option in the upper right hand corner. Click it, authenticate your Last.fm account, and let the jamming begin. From then on, Cloud Player will scrobble anything you listen to from that browser to Last.fm.
Amazon Cloud Player with Last.fm Scrobbling for Greasemonkey
You can contact Whitson Gordon, the author of this post, at whitson@lifehacker.com. You can also find him on Twitter, Facebook, and lurking around our #tips page.