If you want to see the listings that a Contact has marked as a Favorite, Possibility or Discard within their Portal, go to My Matrix> Contacts.
There are columns on the right side of the screen that will show you the number of listings each contact has marked:
You can click on the number to view the actual listings in that specific category.
You can also use the Recent Portal Visitors widget on the Matrix home page to see listings that a Contact has marked within their client Portal.
Click on the number next to the icon (in this case, the Favorite heart) to see the actual listings that were marked.
You can then view them in a different display, send out ShowingTime showing requests to their list agents, plot them on a map, etc.
You can also set up Portal Notifications. Matrix will send you an email or text when certain events occur (portal visit, marked favorite, notes added, etc.).