Metonymy is a project mainly written in RUBY and SHELL, it's free.
this is an image {up,down}load webservice which caches locally, stores in s3, and produces thumbnails in the background using delayed job
an image {up,down}load webservice built on top of the sidetrack framework: http://bit.ly/sidetrack_github. this little webservice caches GET requests locally, stores uploads (originals + thumbnails) in s3 via POST, records metadata in mysql, and produces thumbnails using paperclip in the background using delayed job
check out: http://bit.ly/upORdown for a wee bit more info
rock it!