Add Favorites feature to web site

[login to view URL] is a listing of over 200 deals of the day that is updated throughout the day. I would like for users to to be able to select their favorite sites and display only their favorites. Each site has a unique id that is stored in a database - I'd like for the id of the favorites to be stored in a cookie so a login isn't required to use the feature. The site used to have this feature and it's possible that the some of old code could be reused.