Is there a way to disable the command+up/command+down key combinations? Command+Left and Command+Right are both incredibly useful key combinations. By contrast, Command+Up and Command+Down are incredibly irritating. I almost never actually need a shortcut to the top of the document. 99 times out of 100, when I press Command+Up or Command+Down, it's by accident, usually when meaning to press one of the useful combinations. Is there any way to switch those two off?
You can use KeyRemap4MacBook with a private.xml such as this:

&lt;?xml version="1.0"?&gt;
&lt;root&gt;
  &lt;item&gt;
    &lt;name&gt;Disable ⌘↑ and ⌘↓&lt;/name&gt;
    &lt;identifier&gt;DisableCMDUPandCMDDOWN&lt;/identifier&gt;
    &lt;autogen&gt;
      __KeyToKey__
      KeyCode::CURSOR_UP, VK_COMMAND | ModifierFlag::NONE,
      KeyCode::VK_NONE
    &lt;/autogen&gt;
    &lt;autogen&gt;
      __KeyToKey__
      KeyCode::CURSOR_DOWN, VK_COMMAND | ModifierFlag::NONE,
      KeyCode::VK_NONE
    &lt;/autogen&gt;
  &lt;/item&gt;
&lt;/root&gt;


Just CURSOR_UP, VK_COMMAND without | ModifierFlag::NONE would also disable for example option-command-up.