WinMaximumize allows you to expand a selected window within the free space between windows. The default hotkey is Ctrl+F1. You can change it by clicking on the icon at the system tray. WinMaximumize main window will pop up and let you choose the hotkey. Every change will take effect immediately. Next, simply click on a desired window and press the hotkey that you configured. The window will span according the available space.
||.NET Framework 3.5