Magnet Window Manager - Magnet Developers
New Tab by Flickr - Get a beautiful photo each time you open a new tab
Spectacle App - Move and resize windows with ease.
Momentum - Agile goal and performance management
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).
Gratitude Flow - Gratitude Flow is a web extension that allows you to share and receive gratitude on your new tab with real people around the world.