S3FUSE is a FUSE based filesystem written in python that uses SDB for metadata and S3 for document storage. Using these scalable services available from Amazon, it is possible to mount a user-land filesystem on Linux and FreeBSD. You can even use it on an EC2 instance and then share it via samba to windows computers. Since it uses S3 and has little to no caching, it can be mounted in multiple locations without worrying about the system getting out of sync.

S3FUSE also provides a programming interface for getting S3Files out of S3 and SDB from within your applications.

Note due to the beta nature of SDB, this system is not yet ready for public use. As it turns out, SDB is caching which causes issues when trying to use it to store metadata. OSs don't like being told they didn't just create a file.