Windows: One of the most tedious parts of dealing with photos taken from your camera (or phone) is sorting through the 20 pictures you took to find the two good ones. PhotoSift does that job quickly, with plenty of keyboard shortcuts.
When you first start the app, you can drag any number of pictures into PhotoSift. Once you set a target folder (where you'll place the good ones you want to keep) you can press the left and right arrow keys to move between them. Press F9 to move a file to your target folder for later. You can also make basic changes such as rotate the image (Ctrl-Shift-Left or -Right), or rename the file (F2). The tool is very basic, but does its crucial job much more quickly than browsing through folders.