**Hikari Unicornified Gravatars** converts avatars from people that don't have a Gravatar, into customized unicorns.
At the moment it's not possible, but in future versions this feature will be added :)
Well, if somebody develop an equivalent Gravatar-compatible algorithm, then yes, it could be possible. In future versions I'm gonna allow changing the service URL, so that the plugin can be used elsewhere in case other services like this show up.
Sure, just use the
get_avatar() WordPress function anywhere you want, as you do normally!