More than ever, we spend countless hours working on fancy multi-monitor setups. On Windows, splitting a monitor into two equally sized windows is not always optimal (for example when taking notes next to a browser).
Brought back from the dead (Windows 95 times), Microsoft PowerToys is a utility that does many clever things. Its FancyZones feature in particular allows you to “snap” windows to regions on your monitor that you define yourself. Split your monitor into any number of regions and increase efficiency instantly!