Mac: Mission Control's window organisation makes it a little easier to use than previous versions of Exposé, but seeing individual windows can be hard. Here's a shortcut that can spread an app's windows out so you can focus on one of them.
Tagged With window management
Windows: reSizer is a tiny utility that moves, resizes, repositions and tweaks the appearance of open applications and windows with keyboard commands and hotkeys. As long as the app is running, you don't need to take your hands off the keyboard just to reposition one window next to another or change the transparency of the window on top.
Mac OS X doesn't offer the ability to automatically maximise a window to fill the screen, which can be very frustrating if you prefer to work without distractions (and doubly so if you're on a notebook with a relatively small screen and have come from a Windows background). Free utility RightZoom solves that problem, changing the green window control from "expand to appropriate size" to maximising to the full width and height of the screen (less the Dock).
The highly anticipated (and controversial) GNOME 3 desktop environment released its final version today, adding better hardware integration, window management and application management to Linux.
Windows/Mac: Divvy takes Windows 7's window-lock Aero Snap powers to the next level — originally on Macs, and now on Windows, too. Using a small Divvy windows, or keyboard shortcuts, you can line up your app windows any which way you want.