Chrome: There are a ton of apps to block distractions online, but most of them only do that one thing. The Chrome extension Focus goes one step beyond, giving you a to-do list and a schedule to get things done as well. Focus — not to be confused with the Mac app of the same name with a similar purpose — lets you choose which websites you're going to block. By default, it will only block your distracting sites for 25 minutes at a time (based on the Pomodoro technique).
While most distraction blockers would end it here, Focus also gives you a handy to-do list as well. Here you can add the items you need to get done while you work. When you mark those items as done, they get added to your work log. At the end of the day, you can see what you got done during which time frame. It's a handy addition to a tool that's already pretty helpful.