[swindsor]

Dragonfly looks pretty cool. I like the approach of using rack (our app was written pre-rack, but it's been upgraded to newer versions of rails, so we could make it rack-enabled).

Have people written different datastores (like S3?). I love the idea of a modular, pluggable image server that can choose different backends based on business need/scaling.

Luckily, we deal with pretty small pictures since they are just pictures of our users & their classes. We don't really have any need for handling larger sizes, and our biggest use cases surround generating thumbnails (similar to many social networking web apps).