The Gitiles plugin for Gerrit allows you to list and browse all your Gerrit repositories using Gitiles.
Once you have installed the plugin, run java -jar gerrit.war init -d my-site to configure Gitiles as your source browser for Gerrit, replacing gitweb. The plugin points Gitiles back at the running Gerrit server for things like Change-Id links, so you can be up and running with no additional configuration. If necessary, though, you can put additional Gitiles configuration in etc/gitiles.config.
Gitiles uses Gerrit access controls behind the scenes: the only repositories listed are those that are visible to the current user, logged in or not, and branch-level access controls are applied as well. Objects can only be looked up by SHA-1 if they are reachable from a visible branch.