Edabit is a programming tutorial site that goes beyond teaching basic syntax, and focuses problem-solving skills and how to "think like a programmer." Instead of just showing beginners how to code and stopping after basic syntax, Edabit encourages users to actually make stuff.
Sort My List is an example of a tool that does one thing and does it well. Copy and paste your list into the app, and arrange it how you want. You can also clean it up, find and replace text, change cases, and add different separators if you use multiple columns.
Ever find a leaf and wonder about the tree it came from? Leafsnap is a series of electronic field guides being developed by researchers from Columbia University, the University of Maryland, and the Smithsonian Institution. The free mobile apps use visual recognition software to help identify tree species from photographs of their leaves. They contain beautiful high-resolution images of leaves, flowers, fruits, petioles, seeds and bark.
Need a quick and easy screenshot tool? Try Lightshot. Works on both MacOS and Windows, can be used as a standalone app or a browser extension, and has some editing tools as well.