follow, subscribe

If you are just looking to provide a list of sites on which they are a user, when logged in a user should see the “My Sites” drop down containing links to their sites. In the dashboard, there is also a “My Sites” page at wp-admin/my-sites.php with the same info.

If you’re allowing registration on your network, a user could register for a site and then have it appear under their “My Sites” menu. Here’s a tutorial on how to enable registration.

There are also plugins that allow you to customize “My Sites” or add it to a page, like Enhanced Admin Links in Multisite ‘My Sites’ Drop-Downs or Multi-Site Site List Shortcode.