The Shiba Gravatar Plugin allows you to cache gravatar images locally on your server as well as use your own set of gravatar images.
This release updates the plugin for WordPress 3.1. We also expanded the plugin so that in addition to custom gravatar images, it will now cache generated (e.g. monster, identicon, wavatar) and non-generated (mystery man, blank, default logo) WordPress gravatar images.
Here is a detailed description of the Shiba Gravatar Plugin.
1. Set Gravatar Settings
After installing the plugin, first go into Settings >> Discussion. Scroll down to the bottom of the page, to the gravatar settings section. There should now be a new option called Shiba Gravatar. If you select Shiba Gravatar you can assign your own default images to comment authors that are not registered with gravatar.com.
Select the gravatar setting of your choice and Save Changes.
Note – If you select one of the generated gravatars the plugin will try to cache ALL of the generated gravatar images. Depending on the number of unique comment authors on your site, this may end up being a lot of cached images. Only select generated gravatars if you have a manageable number of comments.
2. Assign and Cache Gravatar Images
Cache your gravatars by going into Comments >> Cache Gravatar.
From this Cache Gravatar screen, you may cache or update your blog gravatar images. If you are using generated gravatars, make sure to always Clear Cache before doing Cache Gravatars.
To use your own custom images, make sure that your gravatar settings is assigned to Shiba Gravatar in step 1. Then, assign your own set of custom gravatar images by clicking on the Assign Gallery link.
Here is a step-by-step tutorial on how to set your own custom gravatar images.