I follow people on this forum that I'm interested in the content of. I also tend to follow people that I'm interested in their browsing habits. If I have a couple minutes online, I'll look at my online list of people I follow and click their avatars to see what they're looking at to see if the thread has any interest to me. It's easier to find content I may care about when I only have a couple minutes rather than looking through the recent activity page myself.
I'm not really sure how to make the features more useful other than to make them more prominent. Right now, the news feed is rather hidden and following people doesn't do much.