I'm a long-time user of JungleDisk,the software that allows you to access your Amazon S3 space as if it were a hard drive. During their beta period were free, but now they charge a small amount. They keep improving their software and truly are committed to offer a multi-platform solution. They now offer a version in which you can mount your JungleDisk using fuse right into your file system under Linux. It's still a beta, but it works well. As part of "Jungle Disk Plus" (their monthly subscription option -- free for the first year) they now also give you web-based access to your files, which is very convenient.