Love the custom S3 backing especially and the speed you guys move at (Lightroom support and Android updates came out so fast) as well as your amazing support (don't know how Amy puts up with me)!
Just recommended you to a friend in fact :)
The only thing I'd change at the moment would be to make a Cloud backend API so that customers can plug in Dropbox, Google Drive, Box.net etc. with something simple like a URL, separating storage from display etc.
Oh and it'd nice to have the option to pay you $2 or $3 since I'm using S3 :)