For example, I just seen post in general about what kind of lights one should get for a mobile gig. It would be cool to have something anyone viewing the thread can click on to show interest in the topic also. Example, "5 others would like to know". Sometimes people will automatically say omg search it! etc But if they see that other people are also interested, they won't reply with a know-it-all response.

Sort of like FB's "like" feature

What's that?

The button on facebook where you can click on "Like", then the displayed counter for the "people who liked this post" increases.

+1