Another idea would be for the classification of favorites to be organized in (user managed) folders rather than colors.
The idea is when you click the favorite icon to get a popup to either add the post to an existing favorites folder or create a new folder (like done in ebay watch list).
Unlike voting, which is for the system and everyone else, marking posts as favorites is for you. Go to your user profile, and you will see there is a "favorites" tab. Stuff you mark as favorite shows up in this list. This is basically a way for you to make your own private list of posts kept for you by the system.
There is one side effect seen by others ...