Hi, in a webapp I'm building there is a planned side feature of supporting product illustrations and manuals (so pictures and PDFs), possibly arranged in galleries. As I'd rather not implement from scratch all of the uploading, managing and serving of this content, I'm looking for existing solutions which I could integrate.

For example, I'm considering Flickr--users of webapp specify their Flickr username and then use some naming convention to link objects in my webapp with pictures uploaded in their Flickr account. Very little code to write from my side, maybe just some API calls that proxy Flickr APIs, since Flickr would handle picture uploading, organizing them in sets, storing them in cloud and serving them in various sizes etc. One drawback here is that either all of the the pictures are public or I have to deal with interactive Flickr authorization. Also not sure if Flickr would be happy being used in such manner.

What other online services or libraries/frameworks I should look at? My webapp is written in Python/Pylons, so Python libraries would be preferred. I'm already using some of Amazon infrastructure, so frontends to Amazon S3 would be cool. For online services, RESTful API would be nice.