Facebook's API (both the new Graph API, and the old REST one) supports this (it allows access to the URLs, and the terms do not prohibit this). I have personall

Facebook's API (both the new Graph API, and the old REST one) supports this (it allows access to the URLs, and the terms do not prohibit this). I have personally written an application that allows the downloading of photos. I think it would be nice if this was supported in a more straightforward fashion (e.g. a large "Download" link on every album), but I think it would be better for Facebook to concentrate on storing photos in their original size, or at least better educating people that their photos are being downsized upon storage.