Web Based downloader for Amazon S3

We need to create a web based tool which allows multi-file downloads from an S3 Bucket. This interface needs to allow a user to provide credentials which allow them to access only one bucket on and S3 server. They need to be able to select multiple images with thumbnails and then click "download". The tool will then need to download the selected images to the users computer, into a directory they've chosen. The script will reside on a php web server but we could use Flash, Java or PHP to accomplish this. I'll need to see some sort of example of previous work or a proof of concept before the project is awarded. Also welcome suggestions on how to accomplish this.