-included in eg, a comment post via a template. Possibly included in a
-recentchanges page item via that template too?
+included in eg, a comment post via a template.
+
+An optional second parameter can be included, containing additional
+options to pass in the
+[gravatar url](http://en.gravatar.com/site/implement/url).
+For example, this asks for a smaller gravatar, and if a user does
+not have a gravatar, uses a cute auto-generated "wavatar" avatar.
+
+ \[[!gravatar user@example.com "size=40&default=wavatar"]]
+
+The `gravitar_options` setting in the setup file can be used to
+specify additional options to pass. So for example if you want
+to use wavatars everywhere, set it to "default=wavatar".