You can mark a site as a favorite to add it to the Favorites list in the Sites menu. This lets you quickly access the site from anywhere in Alfresco. You can mark any number of sites this way.
While in a site, open the Sites menu on the toolbar and click Add Current Site to Favorites.
Note: If a site is already a favorite you instead have the option to Remove Current Site from Favorites.
The current site now appears in the Favorites list in the Sites menu and the My Sites dashlet.