Maximize All on a PC

Use WinKey+Shift+M to restore minimized windows to the desktop.

Use WinKey+Up Arrow to maximize the current window.

Use WinKey+Left Arrow to maximize the window to the left side of the screen.

Use WinKey+Right Arrow to maximize the window to the right side of the screen.

Source.

1. Open Windows Task Manager ( Ctrl + Shift + Esc).
2. Make sure the Applications tab is selected.
3. Go to the menu item Windows, then select Maximize.

This will maximize all windows regardless of their current state.

Well, I doubt that it is really the answer that you are looking for, but on Windows 7, you could save this as a powershell script somewhere:

$dllInfo = '[DllImport("user32.dll")] public static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);'
Add-Type -MemberDefinition $dllInfo -name NativeMethods -namespace Win32
foreach($proc in Get-Process){
    $hwnd = $proc.MainWindowHandle
    # Restore window
    [Win32.NativeMethods]::ShowWindowAsync($hwnd, 4) | Out-Null
}

Then bind a key to run that script.