So the Amazon App Store went live briefly but went back down, hopefully will be back up by morning.
As a surprise, I give you the Amazon App Store .apk you can download and install on your phone! http://amzn.to/getappstore
Also, from what I read the app store is available for US customers only at this time.
Angrybirds Rio is available for FREE for today only and one of the features of the Amazon app store is they will be offering ONE paid app for absolutely free everyday! Read more here [Updated] The Amazon Android Appstore Now Live – Angry Birds Rio Is The First Free App Of The Day
When the Android appstore comes back up, try out the Test Drive mode - it runs supported apps right in your browser using Flash.