Wordpress Plugin for making certain posts a favourite

Here is the situation.

I creat Community websites and give each business/group their own post which they edit rather than create a new one.
I do this for two reasons…
firstly the amount of one paragraph posts you see when you give people the ability to create them…they look so sparse
secondly it saves room on the server because I have a lot users

What I need the ability for someone to follow a post of say a Boutique who updates their deals each tuesday…that they will be saved to a favourites list or pinned to the top of a page etc…

There must be multiple ways of doing this.