Pinterest is the latest social media site where you post your interests and can find subjects of interest to you. Just a few of the categories I'm following and will eventually will 'pin' to are:

Men's apparel, woen's apparel, Pets, technology, science, humor, food and drink, home and travel.

There are many more categories that may interest you.

Basically, you sign up and will receive an invite where you create your user account, then happy surfing. It's amazing how many people have already created accounts and begun pinning.