I agree that Dropbox is not very good at sharing photos. The solution really has to start much earlier in the tool chain, ideally with the camera itself, or the tool that downloads them. Smart phones are great with this, since you see share options right after snapping a photo. iPhoto also has fairly decent sharing options (resizes images, creates web albums, etc). But once you're outside of the realm of camera and photo apps and working with general purpose tools like Dropbox, it gets a lot more difficult.