Exclude the current node from a list view
In some situations, for example a block listing nodes related to the node being viewed, you might wish to exclude the current node from a list view.
Using Views module, add a "Node:ID" argument type to your view. In the Option dropdown, select "Not Equal". Then place the following in the Argument Handling Code:
if ( ($type=='block') && is_numeric(arg(1)) ){
$args[0] = arg(1);
}
return $args;Adapted from this forum post: http://drupal.org/node/131482