Many years ago, I created an Automator workflow that creates a floating screenshot using a web view. I use this almost every day so that I can keep a reference of a chunk of an email, a before/after version of an image, even a snippet of code from Stack Overflow, front-and-center above all other windows. (Especially useful on small screens!)
I got to wondering whether I could improve this using Keyboard Maestro, and not surprisingly, I could.
This macro will create a screenshot using the cmd+shift+4 style selection (window or crosshairs) and then float that screenshot above all your other windows. Thanks to KM8, it is resizable and will automatically scale the image as you resize the floating window.