Have you discovered Pinterest yet? I've been on it for some time now and it is a great way to mark those favorite things you come across on the internet. It is like having a gigantic message board on your computer that you can pin your favorite links and then find them easily again later.
Like facebook, you can also follow each other or just certain boards with topics of interest, as well as leave comments. I added a link to my Pinterest boards to the sidebar on the right of this blog if you want to check it out and follow me.
Have fun pinning!