S3Anywhere is an Amazon S3 file manager for Android Handsets. It allows managing several S3 buckets. It comes with both handset and S3 file managers. It provides download and upload features.
AndFTP is a FTP/SFTP/FTPS client for Android devices.
BucketUpload is a file uploader for the Amazon S3 service. It can be used for personal or corporate backup, as a remote drive or file sharing.