Plugin maintainers and developers of other plugins depending a given plugin may be interested in the version statistics published for a plugin at:

http://stats.jenkins.io/pluginversions/ARTIFACTID.html

This URL exists for every plugin with usage statistics (i.e. when and only when we show the installations graph on the plugins site). If a plugin has usage statistics, a link to the specified URL should be shown on a plugin's page on the plugin site.

Developers of other plugins may be interested in the Javadoc published for any given plugin at:

http://javadoc.jenkins.io/plugin/ARTIFACTID

Not all plugins publish Javadoc, plugins that do are listed in http://javadoc.jenkins.io/plugin/index.json . This URL should be a configurable parameter to the plugin site. The contents of this URL may change over time, this should be taken into account. If a plugin is listed in the JSON file, a link to the specified URL should be shown on a plugin's page on the plugin site.

Not sure where this should be added on the plugins site. It's not relevant to everyone, but it would help if this were still easily discoverable. In the sidebar perhaps, similar to the link to the wiki page?