The Gravatar Ruby SDK by Gravatar can generate image URLs and communicate with the XML-RPC API. The SDK aims to be useful to implement avatar photos in an application. Resources include installation, usage, and configuration.
The popular picture-sharing empire behind I Can Has Cheezburger lets you view, caption and share funny images. You can do this via its sites and, the now, thanks to their API, you can do it via code (technical details at our Cheezburger API profile).