How can I add a menu of local Trac projects to templates/site.html?

I have multiple Trac projects with different environments on the same server. I would like to have a list of links to all projects at the top of each project page so I can quickly switch between them with out having to go up to the top level list at /projects/.

The ideal solution would:

not require loading all the Trac environments on every page load.
update automatically when a new project is added.
only require editing the config and/or templates or add a plugin.
work for Trac 0.11.

Solution

The NavAddPluggin allows the main trac navigation bar to be customized. You could add menu options for each trac of your projects. To add a new menu item the following is added to the trac.ini file.

[navadd]
add_items = project1
project1.target = mainnav
project1.title = Project One
project1.url = http://webserver/trac_project_1

To sort the order edit the mainnav option in the trac.ini

mainnav = project1,wiki,timeline,roadmap,browser,tickets,newticket,search