Combined Board Game Library - A web utility that uses the BoardGameGeek API to show the combined collection of a group of players
Reddit Robots - A bookmarklet that gives a unique icon to every comment on a Reddit thread. Uses icons generated by RoboHash.
Checklist Shuffle - A checklist app that allows users to create a checklist where some items can be postponed while others need to be completed to move on.
Background Pomodoro - A browser-based Pomodoro timer that can run in the background and alerts the user when workcycles begin by subtle sounds and notifications.
Chromecast Gallery - A gallery that cycles through Chromecast background images. It uses the list of Chromecast backgrounds maintained by dconnoly. You can also see it on CodePen.
Print Test - This page can be used as a quick test to see if your browser supports CSS page break styles.
Links to Other Interesting Things
The Design of Everyday Things By Don Norman - A book that discusses the design of various things, hilighting both clever bits of design you'd never think of, as well as how they can be improved. For a taste of what kind of things are discussed in the book, you can watch this Vox Media video on Norman Doors.
CGP Grey - A YouTube channel full of animated videos explaining a wide variety of topics including astronomy, automation, history, and voting systems. My personal favorite is Which Planet is the Closest.
Med School Insiders - A YouTube channel that's primarily aimed at medical students, but a lot of the content applies to anybody looking to manage their time more effectively.