See it in work:
And the easy config via user's profile:
Just like many other people before us, even we once began to wonder how to favorite a user on Stack Overflow (or any other Stack Exchange site). When you stick around the same topic on Stack Exchange for a time long enough, you'll get to meet the same people again and again. Some of them will prove themselves to be right very often, others will even be developers of the discussed technology, so they'll be right every time, some will be famous, too. We wanted to immediatelly see those people's answers and comments when we came across them, because they'd sure be worth it. However, the response to favorite users / friends / private messages requests has always been the same:
Repeat after me: SO is not a social networking site.
Right. While that's probably true and we mostly agree with it, is there really no way to follow a user?
You can follow their RSS feed. Scroll all the way to the bottom of their user page. The RSS link is on the right.
Now that's something, isn't it? No. It's not. We suspect this to be a feature only to make masses quiet. There's hardly any useful application of this except getting noticed about friend's every move, so one could automatically upvote it. We don't want to stalk anyone!
The FriendOverflow app is a step forward, but in a different direction than we'd like to see. We just couldn't find a script/addon that would suit all our needs, therefore ... here it is: The Stack Exchange Favorite Users addon which allows you to highlight posts written by your favorite users.