I was just searching some stuff related to CF users, and I accidentally found a feature , about which I didn't know as a 3 years user of Codeforces. In short, you can create a list of users (who are interesting for you), and easily track their problem solving activity during the rounds, in the problemset, etc. You can find the "LISTS" feature in your profile page.

I guess a lot of people never heard about this, so i wanted to share with you.

Read more about the feature here