Magnet Window Manager - Magnet Developers
DeskPins - DeskPins can be used to make any application topmost, that is, to keep it above all other windows.
Spectacle App - Move and resize windows with ease.
Skybn Window On Top - Window on Top can be used to make any application topmost,that is to keep it above all other windows.
Moom - Move your mouse over the green zoom button in any window, and Moom's mouse control overlay will appear (as seen in the above animation).
PinWin - Download PinWin - Pin On Top for free. Pin any window to be always on top of the screen. PinWin is a minimal Windows system tray application that allows you to pin any windows to the top of the screen with one click.