Mac: One of the minor annoyances for some people on a MacBook is that you can't customise the mouse acceleration settings by device. Acceleration is great for trackpads, but often it's awkward with a mouse. Smooth Cursor is an app that allows you to change the acceleration by device.
Smooth Cursor allows you to control the acceleration for both a mouse and a trackpad separately. So, if you like the feature on one of your inputs, you can use it and customise it while disabling it on the other. It's a simple app that takes care of one of the annoyances on Mac laptops that has bugged me for years.