So? This is actually a feature request!
It happens sometimes that I 've found a problem on CF and right now I am busy with my exam preparation or just I have no time right now to solve this problem. But I wish to solve this problem later because the problem is so interesting to me. But Unfortunately sometimes I lost the problem and can't remember the problem id/link :( .
In this case isn't it helpful to have "My To Do List" of problems where I can find those problems which I 've previously marked as interesting/added in my to do list and I wished to solve it later? This list could be private, only I can see the list in my profile. And whenever I solve a problem from my to do list it will automatically removed from my to do list.
I think it will be helpful for lots of people. Though I know I can keep those problems in my browser as bookmarks but I think rather than keeping a lot of bookmarks of problems, this To Do List could do better.
This feature already we can see in Codechef