Spectacle!

BetterTouchTool is a great, feature packed app that allows you to configure many gestures for your Magic Mouse (1 & 2), Macbook Trackpad and Magic Trackpad (1 & 2) and also Mouse Gestures for normal mice. It also allows you to configure actions for keyboard shortcuts, normal mice buttons and the Apple Remote. In addition to this it has an iOS companion App (BTT Remote) which can also be configured to control your Mac the way you want.

Aquasnap is a powerful window manager that helps you arrange and organize multiple applications on your desktop with minimum effort. It allows you to achieve maximum multitasking, especially if you own a high-resolution monitor or a multi-monitor setup.

ShiftIt is an application for OSX that allows you to quickly manipulate window position and size using keyboard shortcuts. It intends to become a full featured window organizer for OSX. It is a complete rewrite of the original ShiftIt by Aravindkumar Rajendiran which is not longer under development.

Preme is a free software for Windows which lets you add cool desktop features and enhances the desktop functionality.

BetterSnapTool is a utility that mimics Windows 7 Aero snap, allowing you to easily manage your window positions and sizes by either dragging them to one of your screens corners or to the top, left or right side of your screen. This lets you easily maximize your windows or position them side by side.

AltDrag allows you to move and resize windows much easier. When you have it running you can simply hold down the Alt key and then use your mouse to drag any window, and it doesn't matter where in the window you click. This is especially useful in netbooks, with respect to the small screen and touchpad. It simply allows you to do more with less mouse movements.

HyperDock adds Windows 7 like features and more to Mac OS X.

WindowGrid is a modern window management program that allows the user to quickly and easily layout their windows on a dynamic grid.WindowGrid gives functionality to the normally useless right mouse button when moving a window. Doing this will enable the grid snap mode.

Windownaut is versatile window management app that let's you define keyboard shortcuts and active areas on your screen to resize an position the windows on your desktop.

SizeUp allows you to quickly position a window to fill exactly half the screen (splitscreen), a quarter of the screen (quadrant), full screen, or centered via the menu bar or configurable system-wide shortcuts (hotkeys). Similar to "tiled windows" functionality available on other operating systems.

A tiny window management app for the Mac.